20 Upcoming Movies That Have Made ONE Big Mistake

17. Shooting Without A Finished Script - Avengers: Doomsday

There's no denying that Avengers: Doomsday is one of the biggest and most ambitious blockbuster films of all time, with an almost unimaginable number of moving parts which need to be co-ordinated throughout production.

But you'd certainly hope that a watertight script would be locked down before a single frame of the film was shot - yet according to a cast member themselves, that absolutely wasn't the case.

Last summer Rebecca Romijn, who will reprise her role of Mystique in the film, stated that she wasn't actually sure if she'd finished filming her role yet because the filmmakers "haven’t finished writing it."

Even accepting the enormous complexity of Doomsday, encompassing dozens upon dozens of high-profile actors whose availability will dictate what gets shot, it's maddening that a film with a budget of around $400 million has gone into production without a totally concrete script.

Granted, this approach has worked out just fine for the Marvel Cinematic Universe in the past, but considering the entire enterprise is on far shakier ground these days, getting the fundamentals right before rolling cameras seems like the smart move.