When Entertainment Weekly asked Fantastic Four: First Steps director Matt Shakman if Downey Jr. filmed that post-credits scene, the filmmaker pleaded the fifth. "For others to talk about," he teased. However, Shakman did reveal that it was the Russo brothers who helmed the post-credits scene since it was shot for Avengers: Doomsday.

First Steps' includes two post-credits scenes. Here's how that big reveal sets up what's coming in Phase 6 of the MCU.

A good chunk of Doomsday could focus on a clash between Avengers and X-Men with RDJ’s Doom cackling in the background, with a kidnapped Franklin by his side. The premise certainly gives the Fantastic Four a reason to breach their multiversal walls and zip over to 616 to meet the New Avengers.