Most of the comedic relief in Avengers: Endgame was left to Tony Stark/Iron Man, Thor, and Scott Lang/Ant-Man, and rarely did Steve Rogers/Captain America get a chance to throw in a funny line. However, one of the most famous lines from the movie was uttered from the Chris Evans character and just happened to be one of the funniest moments in the film. After the Avengers traveled back in time to the Battle of New York, Tony Stark made a comment to Steve Rogers about his outfit and how it “did nothing for [his] a**.” Scott Lang jumped in and commented that Steve had “America’s a**,” but the joke didn’t end there.
After present-day Captain America faced off against Captain America from 2012, the latter was left lying on the ground with his butt in the air. Present-day Steve Rogers then commented to himself, “That is America’s a**,” and it was one of the movie’s highlights. It turns out, that line was never in the original script. Endgame writers Christopher Markus and Stephen McFeely recently noted (via CinemaBlend) that the line was added during reshoots, and it happened to be the last line Chris Evans spoke for the movie and the last scene he filmed.
“It’s a little meta. Chris Evans has never been comfortable with that outfit from the first Avengers movie. And so in the rearview, it’s a little way to wink at how that was then, and this is now. And then it sort of just built from there. By the time we got to the fight scene where he defeated himself, his butt is on the ground and he was just sitting there for a callback,” McFeely remembered.
Chris Evans once said in an interview that out of all his Captain America outfits from seven different films, he disliked the original Avengers outfit the most. The Endgame joke was a great way to poke fun at the outfit he hated despite the fact that he was also wearing it at the same time. Evans also didn’t appear to be a big fan of the line either, as he remembered the last line he spoke for the film was “really stupid.” Although he wouldn’t clarify what it was, he did say it was in response to something Scott Lang said.
McFeely also noted that the a** joke built up over time, with it only being Tony Stark who made the joke. Scott Lang’s comment about the outfit was later added, before Steve Roger’s comment closed out the whole bit.