The Russo brothers say they didn't have a finalized script when they started filming 'Avengers: Doomsday': "We let ourselves be guided by improvisation."

Directors Joe and Anthony Russo revealed in a recent interview with the Associated Press that Marvel greenlit the filming of "Avengers: Doomsday" without a fully finalized script. According to the filmmakers, production began relying on improvisation.

The disclosure highlights an unconventional approach to a major tentpole franchise production, contrasting with the tightly controlled narrative planning typically associated with blockbuster cinematic universes.