La La Land director Damien Chazelle declares his intentions in the film’s opening moments, as a crowd of Angelenos caught in a traffic jam leap into an energetic dance number, using their vehicles and each other as props. It’s an old-school movie moment, all about color, energy, and joy. But Chazelle’s musical has a number of other moods and modes. There’s a tap-heavy, competitive dance duet between leads Emma Stone and Ryan Gosling. In another scene, the duo flies through the air in a melancholy aerial waltz. In a third song-and-dance sequence, Stone’s character and her roommates rush wildly around their apartment, getting ready for a party. Each setpiece is different from the rest. They all evoke classic musicals to some degree — which helps explain the rapturous response from cinephiles — but they employ very different styles.

Creating the feel and the familiarity of those sequences fell to Emmy-nominated veteran choreographer Mandy Moore. Moore has choreographed for TV (Dancing With The Stars, So You Think You Can Dance, American Idol) the stage (including the Cirque du Soleil show My Immortal), and films (including David O. Russell’s Silver Linings Playbook). But La La Land is a new step for her: a popular big-screen musical where dance is a central focus rather than a sidebar to the film.

La La Land is still playing in relatively limited release in a few hundred theaters nationwide, but ahead of its Christmas Day wide opening, I talked with Moore about the film’s many visual references, the underwater dance that didn’t happen, the camera failure that changed the opening number, and Ryan Gosling’s concerns that he’s a “gangly monkey.”

This conversation has been edited for length and clarity.

When I interviewed Damien about La La Land, he emphasized how every aspect of a musical is so interconnected, any changes in a scene would ripple out into other departments. How did that affect your work?

Well, a lot of times, choreography can be the last stop before you get on camera. So many other departments have to pre-do so many things before I ever get to do my job. For example, in the duet Ryan and Emma do up on the hill, for a long time, those lyrics were very much in limbo. And those lyrics informed the choreography, because the dance was crafted based off what they had to accomplish in the scene. We started something a lot of times, and then the lyrics would change, and it was like, “Now the dance doesn’t say what those lyrics are saying.” So that’s one example.

And in the opening traffic-jam number, there was a particular shot toward the beginning where the camera basically does about a 270-degree circle around one of the cars. This had been in Damien’s mind forever, and we had practiced it and choreographed for that camera move. Then we got up there to shoot it, and it just wasn’t working. The camera wasn’t able to get there. The dancers looked odd in the frame. So that was an example of having to change the choreography on the fly. I had, like, three minutes, because on set, time is everything. I was having to change dancers and move them around, which then affected everything else about the shot. Damien was like, “Oh, sorry, did that mess everything up?” Well yeah!

Did working on Dancing With The Stars and So You Think You Can Dance involve a lot of those kind of on-set, grip-and-rip choreography fixes?

My experience in television completely helped me think on the fly, and quickly turn numbers over. There were a couple of times where I’d tell Damien, “Oh, I’ve got some stuff to show you,” and he’d be like, “Really? How? It’s only been a day since I asked you for that.” I am used to having to turn choreography around very quickly. My life in television 100 percent helped me through this process. And with La La Land, I was lucky enough to hire people who also had experience in fast turnarounds. I knew I could trust them to perform at a really high level, time and time again, and for long takes.

Was that the biggest challenge for Ryan Gosling and Emma Stone as dancers, doing these dances as unbroken on-camera sequences?

With Ryan and Emma, we talked about that very early on. I said, “Guys, we’re not shooting coverage on this. There’s no safety net where we can cut away.” We all agreed as a team — Damien, myself, Emma, and Ryan — that that’s what we were doing. And we really worked toward it. There were very few times where we had that moment of “Ehhh, maybe this wasn’t a good idea?” When we shot the hilltop duet, one of the producers said, “Uh, Damien, do you maybe wanna do another camera, just in case we need to cut to something else?” I love him for the fact that he said no. “No, I only want one camera, this is what the shot is, and we’re doing it.” Once you set your mind to that, it’s funny what people are able to accomplish. The pressure people feel can make them perform at a really elite level. Especially when you have people like Ryan and Emma. From the beginning, Damien never wavered from that plan, so we all prepped for it, because we knew what it was gonna take to get there.

One thing that seems especially challenging in the dances is the regimented Rogers-and-Astaire movement, where Gosling and Stone are perfectly still except when they make these sudden, explosive moments to express whose turn it is to communicate a character. That seems like it would take even more training than dancing in sync, because it wouldn’t come naturally. Did this style of dancing involve a lot of physical retraining?

That’s a great observation. Dance is so nuanced, and so incredibly complex, and the best dancers are the ones that make it look so easy. But most of our rehearsal process was fine-tuning about making each moment mean something. We talked a lot about simplicity and gesture and body language. How you hold your head or your hand a certain way says something. It was never going to be the kind of movie where you have 40 dancers, with Ryan and Emma doing toe-touches and flip-turns. That’s not what the film was. So it was all about those nuanced movements.

It takes a lot of practice. We spent hours just talking about shifts in weight, how a step done a million different ways can say a million different things. Luckily, Ryan and Emma are incredible actors, so they’re able to first and foremost, understand intention. That’s first on the list. It’s nice to create with people who want to know why — “Why am I doing this” first, and then we’d get into how to make that happen. I remember Ryan saying something like, “God, I just feel like a gangly monkey here. My extremities are everywhere, and it’s hard for me to control my body.” And then with practice, you get it. With somebody who can coach you through that, and see the little changes in movements. I was ultimately more of a coach in how to make things look correct.

How did you approach the choreography for the flying sequence?

Funny enough, the flying sequence was originally supposed to be underwater. There were always discussions — the initial script says “they do a waltz in the stars.” But Damien wanted to create this feeling of weightlessness, and it was on the table for it to be an underwater dance. My assistants and I took a GoPro to a pool and created and shot an underwater waltz. I bought it back to Damien, and he said it was amazing. But ultimately, the underwater thing was not gonna happen. So the next process was going to a space where they had harnesses. I would go in there with the stunt team and we would experiment with how to hold dance positions while in wires, or how to float and flip and look like you’re walking. There was a lot of space and an amazing amount of time for just experimenting and trying to figure out what those shapes were.

I needed that because I really didn’t have anything to reference. I wasn’t able to say “Oh yeah, there’s a great waltzing-in-the-stars scene in blah blah blah.” Damien did want to reference Wall-E. I think that was the only reference he gave me — the Pixar movie, when Wall-E is out floating in space, and he spins from one side of the screen to another. I was like, “Well, that’s a lot easier to do with animation than with two people!” So that was fun, trying to crack that feel, and figuring out the right tone.

There are some clear visual references to other musicals in La La Land. Others aren’t as obvious, but they’re suggested. Like spinning around the lamppost. Was “Someone In The Crowd,” where the roommates are heading to the party, heavily inspired by West Side Story?

Yes! We talked a lot about that segment being like “I Feel Pretty” in West Side Story. That was the reference. Damien always really loved Jerome Robbins’ movement vocabulary. He just loves Jerome Robbins’ lines, and how the movements feel very strong. But then he also references “The Rich Man’s Frug” from Bob Fosse, in Sweet Charity. Once you actually get into the Hollywood party, he wanted a little less dancing, he didn’t want to be spread out. He wanted the shapes to evoke the same kind of emotion as “Rich Man’s Frug.”

Were the visual references primarily Damien’s idea? Did you bring in your own specific ideas from classic musicals?

I would say it was half and half. There would be times where we would watch something together and someone would say “Oh, I just love how that person crosses the camera,” and I’d put that in my back pocket for when I was creating a dance. “Okay, what about that did he like?” Or “What was I drawn to with that?” And I’d try to understand the essence of the scene, the actual route it took. Because obviously those great musicals are much more than just great steps. They’re incredibly crafted pieces of work. It was so nice to have someone else doing the same kind of geeking out over musicals that I do. Damien and I would watch films and dissect them, and just go “Oh, I love how the simplicity of that handheld camera makes you feel something.”

Of course, the magic that comes with my own creative process, is really getting to work with my assistants in creating the movement. We’re inspired by people like Gene Kelly and Fred Astaire and the greats, but the people I work with are amazing, too.

Are there references in the film that only serious hardcore musical fans would notice?

Here’s a good one. In the hilltop duet, Ryan and Emma are sitting on the bench, doing their little moves side-by-side, and Ryan does this kind of obnoxious tap move. One day we’re rehearing that, and Ryan comes in. He’d been watching old Fred Astaire musicals, and he loved how Astaire would come into a room and do this obnoxious tap sound as an entrance, and everyone would look at him, and he’d just brush it off and walk right on. He loved how this tap step could be an expression of freedom, or a tantrum of some sort. So when he jumped up on the bench, I said, “Well, why don’t we try something there like you’re trying to get your frustration out? You’re pounding that bench because Emma’s tested you a bunch.” That’s where that came from, and it’s not a reference most people would know.

From what I’ve read, you got hired on La La Land because you talked through your vision for the film with Damien, and it matched what he was thinking. What did that initial presentation look like? What was your original plan?

When I went in for my first meeting, they asked me to prepare some ideas about the roommates number, “Someone In The Crowd.” And I said, “This is like ‘I Feel Pretty,’” and they said, “Okay, yes!” It would have been very different if I had said “I feel like this is a Step Up movie.” I think they would have said “We are not on the same page.”

But I also talked about how the feeling I get from these girls was the same feeling I got when I was living with three girls in Los Angeles. We were all dancers, and we would get ready for a night out just like this. I said, “It’d be really cool if — I remember running into my friend’s room, and we’d fall on the bed and laugh, and maybe she’d grab a dress out of the closet and put it on, as if she was trying to fit into it.”

And all those ideas are actually in the film, just about these girls making fun of Hollywood, but also being in Hollywood, and knowing they have to play the game. They have to go to all these parties to meet all these people. They live in the reality of it, but they make fun of it. So when we actually booked that location, the fun part was, I got to go watch the entire shoot, and it was just like a normal night in an apartment with four girls. “We could run in here, and she could kind of make fun of this with a fan, and she should move back like she’s trying to be obnoxious, and then this girl puts the dress on…” I knew it needed to travel, but it needed to be specific to the space. That was a big one for following that initial vision.

The second number we talked about I did was that hilltop duet, “A Lovely Night.” I came in with some ideas and, like using the bench. Very early in rehearsals, my gut was telling me we needed to do something really cool on the bench. So I created a little section for it, and Damien said, “This is great, let’s stay on the bench longer!” There were a lot of those moments. It was fun to have the freedom to talk to the director, to have him be really open to things. It was a very collaborative process.

What wound up being the biggest challenge?

The pressure and anxiety of having to create something that works for all these different elements. I knew this film had the ability to be something really special, and I didn’t want to screw up the choreography. So the pressure I put on myself and my team was probably the only thing that wasn’t fun. And I mean “City Of Stars” was originally going to be a different number that Ryan and Emma sang together, with a dance we created. Then it ended up being more of a montage. We had many rehearsals for the dance, and then it went away, which is always sad. But I felt such beautiful freedom with Damien. I felt very supported. It was nice to go to work every day and feel like my ideas were valid, and that everything didn’t have to be turned around in a week. Television sometimes feels like that — it’s just a factory of movement.

What inspired the opening number?

There really were no references for that one, honestly. The only thing Damien said was, he never really wanted it to turn into some big production number where everyone was flipping of off cars and doing cool steps everywhere and pointing at the camera. He knew it was an important sequence, because it would get the audience ready for what the rest of the film was gonna be. He just said “Once they’re on their cars, I want it to feel strong, like a Jerome Robbins number.” That was really all. So that one was fun, because we just got to create. “Okay, who are these people, and how do they move?”

What was the preparation process like for putting that all together?

It was a very layered process, for sure. The first 90 percent of that number was logistics. And at the end came the steps. Damien and I sat down and talked through where the camera needed to go, what it needed to see. From that, we put together a big model, with Hot Wheels cars, for the layout.

And then we made another model on a massive table with Post-Its as cars. I wish I could show it to you. It was pretty incredible. My department basically crafted the number with Post-Its and these little people, and confirmed where the cameras would be and what we’d see. Then I got a skeleton crew of about 10 dancers, and we all parked our cars in a parking lot and rehearsed moves. I started creating phrases of movements, like, “Track A will be the people who move along the cars, and this is what they do. Track B will be people between cars who don’t travel. Track C…” And so on. I layered the movement depending on people where people were in relation to the cars.

The next layer was casting, and that was a really, really big process. For our actual rehearsal, we had 30 dancers and 20 cars in all, rehearsing in sections. So we would put the cars in one formation and then we would rehearse it up to a certain point, and we’d stop and reformat the cars into in a different position, and continue.

Then came the stunt elements. There’s the girl that flips and the skateboarder and the BMX rider and the free runner. [Stunt coordinator] Mark Kubr and the stunts department worked with me very closely, and with the music department, to make sure all the stunts was on cue. And then we went up to the freeway for about 12 hours the weekend before the shoot. We shut down the freeway from basically about midnight, and did a walkthrough of everything. And then we shot it all in two days the next weekend.

Honestly, the amount of work was insane. It was around 104 degrees those two days, and we had 30 dancers and I think 100 extras on that freeway. There’s a little movie-magic in there for sure, I’m not gonna lie. It was a lot of planning, and then last-moment praying and hoping. And magic definitely happened, for sure.