The epic two-night cross-over event for The CW series The Flash and Arrow (airing December 2nd and 3rd) is not only going to be unbelievably cool for comic book fans, but it’s just fun storytelling on a grand scale. There are laughs, big action sequences, heartfelt moments and a couple of big surprises, all leading up to the sure to be jaw-dropping winter finales on December 9th and 10th.

Following a special screening of the episodes, actors Stephen Amell, Grant Gustin, David Ramsey, Emily Bett Rickards, Danielle Panabaker and Carlos Valdes were joined by executive producers Greg Berlanti, Andrew Kreisberg and Marc Guggenheim to talk about why they wanted to do this big cross-over so soon, making the decision to have The Flash and Arrow fight each other but also team up against someone else, what it was like to do the big Flash and Arrow fight scene, how Team Flash and Team Arrow affect each other, when we might see the next cross-over, what the actors most enjoy about working on each other’s shows, creating the impression that they actually have a lot more money than they have for what they pull off, and how they decide which villains they want to bring on each show. Check out what they had to say after the jump, and be aware that there are some spoilers.

Question: How soon into the development process of The Flash did you decide that you wanted to do a Flash vs. Arrow cross-over?

GREG BERLANTI: At the beginning of the season, we had planned it. The original thought was to try to do an episode earlier, but then as we started to hatch it, we realized how much time it was going to take. But it really was always built in on both shows, in a lot of ways.

Where did the idea originally come from?

BERLANTI: Since we’ve been doing these shows, our greatest joy about them is the universe of them all. So, when we went in to talk about both seasons, this year, with the network, we said, “It’s typical for these kinds of shows to have to stand on their own, and usually you don’t do cross-overs until later. But since these are born out of DC comics, and in the comic books, the cross-over elements are how the characters were born, so we feel like we owe it to ourselves and the fans to do this sooner rather than later.”

As comic book fans yourselves, when you were discussing this cross-over, what had to go in it?

ANDREW KREISBERG: One of the biggest things was the arguments that Dig and Felicity, and Cisco and Caitlin have about who would win in a fight. That was one of the earliest things we had talked about. We’re all fans, and we’ve all sat around, either as kids or adults, and talked about who would win a fight, Super-Man or Batman, or The Hulk or Wolverine. So, the idea that they would fight each other in one of these episodes was one of our earliest ideas, and that the cast members would have that Comic-Con argument on camera was one of our earliest ideas.

MARC GUGGENHEIM: What I love about the cross-over is that it gives you the best of both worlds. We have our cake and we eat it, too. On The Flash, you actually get to see Flash vs. Arrow. On Arrow, you actually get to see the two heroes team up. Those are the two things, as a comic book fan, that you always want to see. You want to see them fight, but you also want to see them get along and stop the bad guy. We got the chance to do both.

Stephen, you had some pretty epic fights in these two episodes. What was the preparation like for that?

STEPHEN AMELL: It wasn’t that much different than a typical episode. I worked with the same stunt team because we essentially lent part of our stunt team to The Flash, and they’ve created their own team. The actual fight with Grant, which we shot over three nights, was a different experience because of the special effects element. But, I think it turned out great.

How much were you actually fighting Grant Gustin, and how much were you fighting the air?

AMELL: I fought the air, a little bit.

GRANT GUSTIN: But, you kicked the air’s ass.

AMELL: I kicked the air’s ass!

Oliver is speaking from experience when he says that Barry and Iris don’t have a chance, but Grant, do you think that there is still some hope there?

GUSTIN: Yeah, absolutely! I keep saying that Barry doesn’t actually have love very high on his priority list right now. As much as he may think about Iris, making that happen isn’t necessarily the most important thing to him right now. But, he’ll always love her. Maybe he’ll take Oliver’s advice and maybe he won’t, but she’s the love of his life, and that’s not going to change.

What’s in store for Barry Allen and Iris West?

GUSTIN: Barry is going to be honest, in the near feature, about some things. I won’t say what that is exactly, but it’s something pretty big.

Emily and Danielle, it’s not often that you guys get to work with other females. Was that fun for you guys?

EMILY BETT RICKARDS: It was great for us. To get to work with another intelligent woman is great for Felicity.

DANIELLE PANABAKER: There’s a lot of trust. They’re both protecting these great men, so they have that in common.

Do they both have feelings for these great men?

RICKARDS: So many feelings.

David, are we going to get to see a softer side of Diggle?

DAVID RAMSEY: I don’t know about softer. That’s about as soft as he gets. The stakes are high. Diggle is working in the field, and he has a potential wife and daughter at home. I don’t know if you’ll see softer, but you’ll see him much more engaged.

Danielle, with the return of Firestorm, how will Caitlin Snow react to finding out that her fiancé, Ronnie Raymond, is still alive?

PANABAKER: She does not handle it well. She’s spent the last year grieving the loss of Ronnie, and then she thinks maybe he’s back, or maybe she lost her mind. Seeing him in a very different form is extremely challenging for her.

Team Flash is much more jovial than Team Arrow. How do you think seeing the dark side of being a superhero will affect Team Flash, moving forward?

CARLOS VALDES: One of the most fascinating things is that when one team goes to the other team, the tone of that city starts to affect them. When Barry, Caitlin and Cisco go to Starling City, it’s very clear to them that they haven’t really been taking this as seriously as they could, and they start to grapple with the stakes. These are life or death situations, and that affects their growth.

BERLANTI: One of the most rewarding parts, for me, is to see the actors cross-over to these separate shows, and how much they hold the screen in the other show. It shows how lucky we are to have amazing actors on these shows. Just because the show is a spin-off, it’s still a whole other show. And they feel like they fit in and they totally owned it, so we’re just really fortunate.

In return, will we see a lighter side of Team Arrow?

AMELL: No.

How do you think Team Flash has affected Team Arrow?

AMELL: I think it is important for us to know that other stuff is out there, like meta-humans. There is a whole team, and it’s nice to stretch beyond Starling City. But that smile that you saw on Oliver’s face lasts about four seconds in the next episode, and then it’s gone.

KREISBERG: One of the best things about reading comic books, when you’re a kid or an adult, is watching the characters cross-over. What happens in one book affects the other, and these shows are so tightly knit that it feels like one giant show. So, as many times as we can, there will be cross-overs.

How soon will it be before we get another cross-over?

BERLANTI: We’re just working on the back half of the year, and there will be other cross-overs. There won’t be a two-parter like this, in the back half of the year. Our finales, that we tend to build toward on both of these shows, are so massive that it would be impossible.

What is your favorite part of crossing over?

KREISBERG: What was fun was that we actually combined the writers’ rooms. We actually had The Flash writers in the Arrow room when we were breaking the Arrow episode, and vice versa. You pick everybody for their specialities and personalities, and then you throw two rooms together and it’s like throwing two casts together. When you look at this, you really see the results of all of those minds put together.

RAMSEY: It’s always the actors, for me. Working with them is just fun. First of all, it’s amazing that me and Stephen even get a word out because we’re just total clowns. And then, you bring the three of [The Flash cast] to the set and it’s just fun. They’re great actors. They fit because we’re working with great actors.

AMELL: The scene where Diggle sees Grant as The Flash, for the first time, you could build an entire blooper reel from that scene. If you watch it again, you’ll see me bite my lip. That was the only way that I could get through it.

KREISBERG: The first take actually got ruined. The first time he threw the fries, the entire crew burst out laughing.

GUSTIN: My very favorite moment from all of the cross-over stuff is the first time that Diggle sees Barry in the suit with powers. We had a lot of fun that morning. It was really early in the morning.

RAMSEY: It was real Coca Cola that we were using, so we were just wired.

VALDES: It’s definitely working with these actors. I had binge-watched Arrow before I was ever even a part of The Flash. So, I knew these faces, in some capacity, and then I actually got to work with them and I was like, “Oh, this is dope!” I really enjoyed that. I also really enjoyed working with the crew.

PANABAKER: It’s getting redundant, but it really is the cast. We all love each other. It’s fun to get to see each other in the trailers and high-five. It’s really special.

RICKARDS: It’s the people we work with, every day. It’s really cool.

On Arrow, you waited a long time to actually give him the name, but The Flash has gotten his name before half a season has aired. How did you come to that decision?

BERLANTI: That was really Geoff Johns. He was just like, “We’ve gotta name him soon,” so we did.

GUSTIN: You were calling Barry, The Streak.

KREISBERG: It fits in with The Flash universe. It’s funny because Arrow influences The Flash. By the time Barry became a superhero, Oliver was already calling himself The Arrow, so it was like, “Well, I need a name.”

Stephen and Grant, what is your favorite Green Arrow and Flash comic?

AMELL: For me, it’s Year One. That was largely the source material for our pilot, and it was the first Green Arrow comic that I’d read.

GUSTIN: When I got the audition, I hadn’t read many Flash comics, if any, before. I knew a lot about him, but I started reading as much as I could. I found the New 52 series pretty early on, and then stuck with that series because it seemed like that’s what we were drawing from the most. It felt the most contemporary, and I liked that.

Grant, are you going to try to keep up with Stephen Amell on social media?

GUSTIN: Stephen is fantastic at Facebook. I will probably never be able to keep up with him, but I’m trying to get better at social media, in general.

AMELL: You’re a better singer than I am.

KREISBERG: You will hear him sing in an upcoming episode of The Flash.

GUSTIN: Somebody else is going to sing with me, too.

You guys really are creating a new era for superhero television, but you have to do all of these big effects and action sequences on a TV budget. Do you keep that in mind when you plan out episodes?

GUGGENHEIM: Much to our line producers’ chagrin, on both shows, we actually don’t consider budget, at all. The first draft of the scripts really show that. And then, we go through a process and we have it down to a science where we shave and shave and shave. It’s about the illusion of creating the impression that we actually have a lot more money than we have.

KREISBERG: Part of that is also the directors that we have. That fight between Oliver and Barry, within the script, that was pretty much exactly what we wrote, and Glen Winter pulled that off in the amount of time and money that we had.

How do you guys decide on which villains you want to bring onto each show?

KREISBERG: On Arrow, it’s a little bit different because Arrow doesn’t have quite the same Rogues Gallery that The Flash does. The Flash has some of the best villains, so there are a lot more to choose from. But, Arrow does have some amazing villains. Obviously, we have Merlyn, played by John Barrowman. And we do have Brick coming on, who’s played by Vinnie Jones, and he’s amazing. That’s a trilogy, for Episodes 10, 11 and 12. It’s a giant three-parter. We pull from everything. One of the fun things of the show is that we can pull from the classic Golden Age and Silver Age villains, but then there’s a bunch of new villains. This season, we had Komodo and Cupid, and they’re more recent additions. And we have a board up in The Flash office of all of the villains that he has. Geoff Johns’ favorite thing to do in the world is to take old, silly characters and make them cool. We’ve gotten pretty adept at taking some of these characters and either Arrow-fying them or Flash-ifying them.

Will we see Killer Frost or Vibe on The Flash, any time soon?

VALDES: We can’t lie and say we haven’t talked about it. But for right now, we’re only really focusing on Caitlin and Cisco.

KREISBERG: Hopefully, we’ll have a long, successful run, and I’m sure, at some point, something like that could happen. But right now, we’re very happy with Caitlin and Cisco being Caitlin and Cisco.

PANABAKER: We’ve got our hands full.

Stephen and Grant, so who would win in a fight, Arrow or The Flash?

AMELL: Diggle would win.

The two-night cross-over event for The Flash and Arrow airs on The CW on December 2nd and 3rd.