The CW’s “Crisis on Infinite Earths” is a crossover event of epic proportions, uniting the superheroes of the Arrow-verse for one common goal – to save the universe. With their worlds in imminent danger, The Monitor (LaMonica Garrett) sends Harbinger (Audrey Marie Anderson) to gather Supergirl (Melissa Benoist), The Flash (Grant Gustin), Green Arrow (Stephen Amell), Batwoman (Ruby Rose), White Canary (Caity Lotz), The Atom (Brandon Routh) and Superman (Tyler Hoechlin) together, in the hopes that together, they will find a way.

After a screening of the first two hours of the crossover, held at the offices of The CW, executive producers Marc Guggenheim (Arrow-verse), Beth Schwartz (Arrow), Keto Shimizu (Legends of Tomorrow), Caroline Dries (Batwoman) and Robert Rovner (Supergirl) got together to answer questions about how this epic event came together, what it was like to coordinate with all of the shows, making the scheduling work, how the previous crossovers helped them prepare for something so big in scope, the episode’s surprise death and the ramifications of that, and all of those cameos. Check back for Part Two of this interview, after the second hour airs.

*Be aware that MAJOR spoilers are discussed*

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Question: For those unfamiliar with the comics, how would you set up “Crisis on Infinite Earths”?

MARC GUGGENHEIM: It’s funny, we’re of the opinion that you don't need any sort of set up. It’s fun to see last year’s crossover, meet The Monitor for the first time, and know that a crisis is coming and that Oliver made this bargain with The Monitor, but you get all of that information in the body of the story. So, you’ll notice that we’re not having any recaps. The only recap that we’ve cut for the crossover is gonna be at the beginning of hour four, which will be in January, because we feel like you can just dive right in. 

All of the shows have been leading up to this crossover, a lot more than they have in years past. What was that like to coordinate?

GUGGENHEIM: It was weird because we basically started breaking out the crossover before we got to a lot of those episodes that lead right up to it. So, there was a little bit of educated guesswork, on our part, on both ends, both in terms of breaking out the story and having a sense as to where all the shows would be, as well as each of the shows, leading up to it. The trickiest, obviously, was Legends. That was a real hard thing because we were breaking hour five, which is Legends 508, before or during Legends 501 through 507.

KETO SHIMIZU: Crisis is essentially a prequel to our Season 5. However, it was shot out of order. So, we had to know the sequel to everything that was gonna happen and in “Crisis,” before we’d even written “Crisis,” which was very tricky for us. We had to know, as we were breaking our first stuff, what was gonna happen at the very end of this crisis, so that we could start writing our season. It was challenging, but I think it actually ended up melding really well.

GUGGENHEIM: It worked out great, actually.

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Image via The CW

BETH SCHWARTZ: And Arrow was actually the opposite of that ‘cause we were going towards the end of our season and series. It’s different than the crossovers have been in the past

Since “Elseworlds,” you’ve been building up just how big “Crisis” was going to be. How do you keep building on things to make it bigger and do something this epic?

SHIMIZU: It needed to feel emotionally significant for everybody. You can have all of these incredible cameos from all of these fun, different versions of these DC characters that we know and love so much, but at the core of it, we really wanted to keep track of the mains from all of our shows and have them go through something really incredibly significant for their characters, in this crisis. And I think that, honestly, is what grounds it and makes this crisis important, on a very deep heart level. You feel for these characters, as they’re going through this amazing adventure together, and it brings them all closer together, which I think is the definition of epic, in terms of the relationship that all of these shows have with one another.

GUGGENHEIM: Those are all of my favorite scenes. The scene that ended this episode, the penultimate scene with Kara and Kate, was so resonant. And they have another scene, in hour three, that pays off the cliffhanger of the second episode, that is phenomenal. Both Melissa [Benoist] and Ruby [Rose] just blow the doors off the place. And similarly, in hour three, there’s a great scene between Grant Gustin and Cress Williams that’s just great. Those are the scenes that really make it live. And yes, we’re gonna throw in as much visual effects and bombast as we can. They’ll be plenty of that.

This is a TV event that’s unprecedented. As showrunner, you guys deal with so many issues in a season, but what were your biggest concerns, going into this crossover?

GUGGENHEIM: Coming out of the crossover.

SHIMIZU: It’s a really tough thing to produce, and I think all of the shows have felt it, in one way or another, and some more than others. It’s a real huge challenge to get the scope and the excitement that we want out of it. The money has to come from somewhere.

ROBERT ROVNER: One of the things that was challenging and unique to this one was just the amount of guest cast that we had, and making sure that we could get those people on board, that we could afford it, and make sure all of their schedules worked out.

SHIMIZU: The scheduling is crazy.

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Image via The CW

GUGGENHEIM: I always describe it as three-dimensional chess with Rubik’s cubes. The funny thing is that it’s an incredibly low tech process. Basically, what we do is that we have a huge board that’s bisected into boxes, and those boxes represent a big calendar. Each of the schedules is color-coded. Arrow is green. The Flash is red. Batwoman was tough. We went with maroon. Legends is grey. Supergirl is blue. So, what we do is that we take all of our color-coded schedules and sit there with a paper cutter, and we move literal strips of paper. Each strip represents a scene, and the goal, after several days, is that hopefully every single strip of paper ends up in one of those boxes, and it has to be on that board. It’s a schedule that’s held together with spit, bailing wire, and hope because, of course, nothing works out perfectly and we have to do a lot of thoughts on the fly. So, if you notice characters moving in and out of scenes, chances are, they’re moving in and out of scenes because of the schedule.

What was it like to deal with the scope of this and how it all came together?

SHIMIZU: We’ve been doing it in steps, with the crossovers. It’s been getting bigger and bigger, every time we do it. Although, last year, we took a step back and took a breath, and then took a giant bite out of the cake, so it’s felt a bit more manageable because of that. Every time we come back to this, we’re like, “All right, we doing this again, and more.” This year, being the biggest and most ambitious yet was very challenging. However, we knew how to prepare ourselves for it, and our support staffs were ready. There was a lot of stuff to keep track of, and a lot of schedules to coordinate, but we started really early. We started almost before production on any of our shows started.

GUGGENHEIM: We actually started right after the summer hiatus. That was when we began.

SHIMIZU: We went into a meeting, all of us together, and started planning this out. And thank goodness we did because it wouldn’t have been possible, if we had started it too late.

GUGGENHEIM: One of the things we did was that the story was designed to be very modular, so that we had maximum flexibility. We’ve also done this before. Yes, we’ve never done anything like this, but we’ve come close enough that we’ve learned a lot of tricks, along the way.

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Image via The CW

Ending the first part of “Crisis” with Oliver dying has effects on many different characters. What can you say to tease what some of those reactions are going to be in Part 2?

CAROLINE DRIES: The leads all have a different take on how to grieve or handle Oliver’s death. Some of them believe that it’s over. Some of them believe that they can fix this. Some of them are not wanting to even think about it. So, everyone has a different approach to it, and that helps generate their story for the episode.

ROVNER: For Kara, in addition to Oliver, she’s grieving the loss of her Earth, so she comes into it wanting to try to figure out how to fix what’s happened. That’s her journey, very much with Kate, not only in the Batwoman hour, but in the rest of the crossover.

Killing Oliver in the first hours will surprise some viewers. Why did you decide to do that, and what affect do you hope that will have?

GUGGENHEIM: Basically, it really came off of “Elseworlds,” which strongly suggested that Oliver was gonna die. And then, in the Arrow Season 7 finale, we told the audience that Oliver’s gonna die in “Crisis.” So, the dilemma that we presented to our own selves was that we spoiled our own story. So, if Oliver dying isn’t the surprise, what is the surprise? We’ve figured the audience is expecting that Oliver would die in the climax, in the fifth hour. So, if we go in the exact opposite direction and killed him off at the end of hour one, we accomplish two things. We, hopefully, do surprise the audience. That’s absolutely the intention. But we also really establish the stakes. Going into the next four hours, if Oliver Queen can die, then no one is safe.

SHIMIZU: And it sets up really interesting stories and conflicts between all of these characters, these leads of these different shows, who have different ways of reacting to this tragedy. You get to see them all grieve together, in a really compelling way.

You’ve also said that Barry Allen is going to die, and you do have people die and then bring them back to life. How do you handle that, knowing that you can’t just kill off all of your main characters?

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Image via The CW

GUGGENHEIM: It’s a good question, but it’s hard to answer without spoiling where we’re headed. Once you see all five hours, all of the twists and turns will feel satisfying and, hopefully, feel earned.

You destroyed Earth-38 in the very first hour. What will the effects of that be, on the characters from Supergirl?

ROVNER: The immediate effects, with Kara and the people that were able to get to Earth-1, they’re stranded there and hoping that the rest of the universe doesn’t fall. In terms of when they come out of this on the other side, I think you’ll have to wait and see.

The cameos in the beginning of the first hour were just brilliant. Are there more to come?

GUGGENHEIM: Yeah. We’re still working on a bunch, actually. I think we considered just about everything there was to consider. Obviously, you don’t want it to be all about the cameos. You want just the right amount. There’s a sequence that’s in one of the upcoming episodes, that’s not dissimilar to the sequence at the beginning of hour one that, if it all comes together the way it’s supposed to, is one of my favorite things.

“Crisis on Infinite Earths” Part Two airs on The CW on December 9th, Part Three airs on December 10th, and Parts Four and Five air on January 14, 2020.