A big X-Men movie mistake from the original Fox series can be rectified in Avengers: Doomsday. Throughout 2024 and 2025, a significant amount of information and details about Avengers: Doomsday have been released. While the overall plot of the movie remains shrouded in mystery, the full confirmation of Avengers: Doomsday‘s cast list came almost a year after Robert Downey Jr.’s return to the MCU was confirmed alongside the Russo Brothers.