Rebecca Romijn let the Doomsday script slip at Comic-Con, and the Russos just confirmed it

Let’s be honest, nobody was ever expecting Avengers: Doomsday to come together quietly. With Robert Downey Jr. making his proper MCU comeback and that enormous X-Men/MCU crossover dangling in the marketing, Marvel’s fifth Avengers film already had fans whipped up into a lather of anticipation and worry. But in amongst all the noise, there was a pretty odd rumbling during filming: the script wasn’t actually finished when the cameras started rolling. Properly unfinished, not just a bit of polish still to come while actors run through scenes. For a film this big, you almost have to admire the nerve.

A script in flux

Filming kicked off in April 2025 and wrapped up five months later, during September. During that window, you had actors dropping hints that things behind the scenes weren't quite buttoned up. Rebecca Romijn — back in blue as Mystique — couldn’t help herself at San Diego Comic-Con. She told a room full of fans and journalists that the Russo Brothers actually hadn’t finished the script. Naturally, MCU folks on social media lost their minds, although some put it down to ‘rumours’ flying about the set. Turns out, Romijn had it bang on.

The Russos admitted to AP News they were deep into filming without a final script, but Joe Russo pitched it as something positive: 'We always view the script as a living organism. We’re improvisation-based, rehearsal-based directors. We like to see what the actors bring to the characters, and sometimes you don’t get the actors until a few days or a few weeks before you shoot them. And a lot of the time, that’s when the magic happens.'

Now, the Russos have always enjoyed a bit of looseness on previous Marvel outings, but by every account, this went well beyond a few script tweaks. This time, significant parts of Doomsday were apparently still up in the air while the crew set up for takes. If you’re sensing that’s less ‘artful creativity’ and more ‘emergency rewrite’, you’re not alone.

Too little time? Hardly

It’s not like the team didn’t have warning — Jonathan Majors was sacked back in December 2023, and that forced Marvel to chuck out the entire Kang Dynasty approach and reboot as Doomsday. But still, they had a solid sixteen months from Majors’ exit to the first day of shooting. The Russos, for their part, weren’t officially signed until July 2025, although the film did already have four writers in the mix: Stephen McFeely, Michael Waldron, Chris McKenna, and Erik Sommers. Even just marking from the Russos’ start, that’s nine months for rewrites and prep. In blockbuster terms, that’s not exactly a deadline from hell.

Filming on Avengers: Doomsday started in April 2025 with the Russos helming — and a less-than-finished script in hand.

Why such a last-minute approach for such a massive project? My guess: sheer chaos, plus Marvel’s ever-expanding checklist of cameos, franchise obligations, and post-Majors clean-up. Nothing the Russos haven’t wrangled before, but this sounds next-level haphazard. They might insist it’s all part of the magic — and maybe on set it felt that way — but someone’s nerves must be shredded in post-production by now. Still, even with all the behind-the-scenes drama, the promise of a true X-Men/MCU event movie is probably enough to keep the Marvel machine chugging into December.