Avengers: Endgame - 9 Possibilities For The Secret New Post-Credits Scene

2. Cap's Adventures In Another Dimension

This is a slightly more left-field choice, but it definitely fits with the idea of the multiverse being open and with the way the Russos mysteriously spoke about Cap's adventures through time in the wake of questions about him messing up the timeline.

Joe Russo has spoken a lot about Cap since the film was released and confirmed that "the old Cap at the end movie... lived his married life in a different universe from the main one. He had to make another jump back to the main universe at the end to give the shield to Sam.”

That might seem like retconning to cover a plot-hole but from other interviews it's very clear that it's not something they conceived on the fly:

“Captain America chose to go back to the past and lived with the one he loved for the rest of his life. The time travel in this movie created an alternate reality. He lived a completely different life in that world. We don’t know how exactly his life turned out, but I’d like to believe he still helped many others when they were needed in that world."

What if the Russos wanted the opportunity to prove that they didn't open up a huge plot-hole, while also offering Cap another tribute by showing him in an alternate reality and potentially hinting that we'll eventually get more Cap movies in the future?

The Russos have hinted previously that we MIGHT get to see something of Cap in another reality at some point and that could very much be a hint at this post-credits scene.