Marvel is always known for guarding their secrets , but sometimes things have definitely changed. A surprising set leak from Avengers: Doomsday has gone viral after a fan reportedly snuck onto the filming location and captured footage of a hidden house entrance, and now various theories are spread across the internet.

The leaked clip, which quickly spread across TikTok and Reddit, shows a secluded, detailed structure that many believe holds a deeper meaning. People are convinced it could be tied to the Iron Fist or even the X-Men, suggesting that Marvel might finally be laying the groundwork for the long-awaited introduction of mutants into the main MCU timeline.
The design of the building also raised eyebrows with its retro aesthetic; it appears to fit perfectly into a 1960s setting, further revealing it will be a time travel film. This lines up with the artwork that got leaked on the internet, suggesting that Avengers: Doomsday will have multiple timelines and alternate realities, possibly bringing back legacy characters or introducing brand-new ones.
Another theory points to Madripoor, the infamous island often tied to Wolverine and other X-Men stories. With The Falcon and the Winter Soldier briefly touching on Madripoor, it’s not impossible that Avengers: Doomsday could explore it in more depth, especially if Marvel is slowly stitching together connections to the X-Men world behind the scenes.
Avengers: Doomsday is set to hit theaters on May 1, 2026.