Spoiler warning: Do not read on unless you’ve seen “The Flash” episode “Legends of Today,” part one of The CW’s “Flash” and “Arrow” crossover event.

After the first hour of this year’s “Flash” and “Arrow” crossover, Barry (Grant Gustin) and Oliver (Stephen Amell) have faced Vandal Savage (Casper Crump), discovered Kendra Saunders’ (Ciara Renee) hidden past as Hawkgirl, and met her reincarnated soulmate, Carter Hall (Falk Hentschel).

And somehow, the episode still found time to see Patty (Shantel VanSanten) shoot Harrison Wells (Tom Cavanagh), prompting Caitlin (Danielle Panabaker) to use an experimental speed-enhancing drug on Jay Garrick (Teddy Sears) to save Wells’ life, and managed to leave us with the cliffhanger of Oliver seeming to realize that the young boy he spots with his ex-girlfriend Samantha (Anna Hopkins) at Jitters is around the right age to potentially be his son, despite her previously telling him that she miscarried their baby.

While that particular plot point is explored in the “Arrow” installment of the crossover, the executive producers of “The Flash,” “Arrow” and the upcoming midseason spinoff “DC’s Legends of Tomorrow” (along with stars Teddy Sears and Falk Hentschel) spoke to reporters about the events of “The Flash” installment.

Animosity of two Earths

Jay may have grudgingly saved Wells’ life by taking the Velocity 6 serum, but that doesn’t mean he and the scientist are about to become BFFs.

“Jay is still very dubious of Wells, and the carnage he’s created on Earth-2; just him being behind the particle accelerator explosion,” Sears noted. “There is a growing understanding, respect. There is a nice — I don’t want to call it a shift, but these two will begin to work side-by-side, as members of Team STAR Labs, going forward and fighting metahumans. They’re not going to be buddies or great friends, but something does happen for the good after that.”

A new kind of speed

Sears also admitted that although Jay won’t be “jonesing for a fix” of the new speed-enhancing drug, “he’s aware of the potential Velocity 6 has on his life. But I also think he’s clear that, ‘I don’t want to go down that path.’ But I think like anyone who has seen the other side, there are haunting memories of what could be, and what could have been.” The inability to be useful is particularly challenging for Jay, Sears notes. “This guy who was able to do a lot of good when he had the Speed Force. He’s wrestling with his identity in a way, and his life without it.”

As for whether Barry will eventually take the serum, executive producer Andrew Kreisberg hinted, “If you’re a fan of the comics, you know that a big part of the comics is Velocity 9. And today you guys met Velocity 6. So it’s safe to say that there’ll be a few more iterations of that formula … How it plays out and how it works and who uses it and the effects that that have — that’s something that you’ll have to watch.”

Close encounters of the Earth-2 kind

Patty has already had a few brushes with Barry’s secret identity and the many secrets the STAR Labs team is keeping, but this week certainly put her in an untenable situation after she shot Earth-2 Wells. It seems like she’s long overdue for someone, either Barry or Joe (Jesse L. Martin) to clue her in, which Kreisberg says is an ongoing part of Barry’s storyline this year, especially given the secrets they kept from Iris (Candice Patton) last year.

“Can he actually have a relationship with somebody, and what does having a relationship with somebody mean?” Kreisberg mused. “You see it moving forward, especially with Barry’s interactions with Iris where Iris is telling him, ‘I’m telling you as your friend that the way you handled things last year were terrible, and you caused a lot of unnecessary hurt and you caused people to be in danger, and you have to do things differently if you really care about this girl.’ Then on the other hand, he has this new version of Wells ironically telling him, ‘if you really care about this person, you keep her as far away from all of this as possible, because if Zoom finds out, he’ll kill her.’ So Barry is really wrestling with those two things moving forward.”

Savage plans

While we know that Savage is fixated on Hawkman and Hawkgirl for reasons that will become clearer in the “Arrow” episode of the crossover, exec producer Marc Guggenheim admitted that there’s a lot about the character that they’re saving for “Legends of Tomorrow.”

“He has a very clear plan and trajectory. The thing about Vandal is that for him a lifetime is an eye blink. He thinks in thousand-year-old terms. He’s a very much a master of the long con,” he noted. “Yes, he does have his own personal agenda vis-a-vis the Hawks. But he’s got much bigger plans for the world, which you’ll have to watch ‘Legends’ to find out. “

Building a ‘Legend’

The crossover was always intended to set up “Legends of Tomorrow,” according to executive producer Greg Berlanti: “The studio and the network were asking us from the very beginning of the year, which characters from ‘Legends’ are going to be in the two-hour, and were encouraging us. We wanted to have some — a couple, but not all in it, so it also felt right that we would use the characters that we hadn’t introduced on the individual series yet, with the exception of Rip Hunter [Arthur Darvill], who we saved for the pilot of ‘Legends.’”

But that set-up also required a lot of logistical maneuvering from all three shows, since “Legends of Tomorrow” had already started filming before the crossover episodes were shot.

“We had known what we had already written into the introductions of ‘Legends,’ so there were several times — and there are characters that I want to wait until people start to watch ‘Legends’ [to talk about] — that you’ll see that there was stuff that we set up in ‘Legends’ and then went back and put into this that then will pay off again in ‘Legends.’ So they really speak to each other in that way,” Berlanti said.

That process was particularly challenging for the actors, especially Hentschel, Renee and Crump. “You had actors who were not only working on different things, but you had Falk and Ciara and Casper who had already been filming episodes of ‘Legends’ … They’d already established them on ‘Legends,’ and then had to go back and introduce them,” Kreisberg added.

Hentschel described the process as “an acting marathon,” before amending, “No, it was great fun. Being carted from one set to another, it was a whirlwind, but it was really amazing to see it come together. When [the producers] all told me about this at first, I was like, ‘how’s this going to happen?'” he laughed. “But it was a blast and I have to say that it was very admirable to see it come together and everybody pulling it together. It was very creative.”

Starcrossed lovers

While Carter had a somewhat aggressive introduction (pushing his supposed soulmate off a roof was certainly an ice-breaker), Hentschel noted that Carter and Kendra “come as a team,” adding, “in my mind they’re like a bickering old couple. And he’s gone through 4000 years of loving her and having her love him back … she doesn’t know about it yet, though, so there’s always this fun dynamic of him being like, ‘You’ll love me! It’ll be good! I’ve seen it.’ And I think underneath it, terrified, always, of losing her because imagine you’ve seen everyone that you know die. It’s pretty lonely and here’s that one person that is always constant. So I just think that couple dynamic between the two of them… I hope everybody will enjoy it as much as I did.”

Kreisberg said that as well as the fun side of Hawkman and Hawkgirl’s banter, there’s also a bittersweetness that will be explored through these episodes and into “Legends.”

“What’s interesting about Carter’s character is he remembers loving Kendra and he remembers all the adventures they had. Not just the bickering, but he remembers all the fun they had. And now he’s staring at this woman who’s looking at him like he’s crazy,” he noted. “There’s a sadness about the whole thing, because he knows how great it can be and how sad it is for him to look at her looking at him like he’s a stranger.”

Click here to find out what the producers had to say about part two of the crossover, which took place during this week’s “Arrow.”