Sebastian Stan revealed that the backpack that Bucky is seen wearing in the trailers contains journals that he has put together of his scattered memories.
The day before filming a fight scene with Robert Downey Jr., Sebastian Stan sent him a video of himself doing intense bicep curls in front of the decapitated head of an Iron Man suit. He attached the message, "Looking forward to our scene tomorrow Robert."
Tom Hiddleston confessed that even though he did not appear in the film, it contained one of his favorite moments in the Marvel Cinematic Universe, the helicopter scene. He enthused, "I mean Chris Evans does a bicep curl, with a helicopter! If you don't love that, we can't be friends."
Tom Holland commented on how intimidated he was when he came to screentest for Spider-Man, saying that Robert Downey Jr. took him aside and said, "Listen, I remember my screentest for Iron Man. I remember how terrified I was. Just think of it as an audition. It's nothing too scary. If you get it wrong, we'll just start again. No pressure."
This movie revealed that Bucky Barnes had been hiding out in Bucharest, which is the capital of Romania. Sebastian Stan (Bucky) is a Romanian-American actor, who was born in Constanta, Romania, and raised there until he was eight. In the first scene set in Bucharest, Bucky is buying fruits from a street market. Stan's native language is Romanian, and therefore spoke it perfectly.
Alfre Woodard: (at around 17 mins) as Miriam Sharpe, the mother of an American citizen killed in the battle of Sokovia. Woodard was suggested for the role by Robert Downey Jr. before Marvel Studios learned of her casting as Mariah Dillard in Luke Cage (2016).
Jim Rash: (at around 16 mins) As the MIT liaison. The Russo brothers previously worked with Rash on Community (2009).
Stan Lee: Stan Lee's second cameo playing a delivery man. In this movie, he played a FedEx driver delivering a package to Tony Stark (Robert Downey Jr.). In Quarteto Fantástico (2005), he played Willie Lumpkin, a USPS mailman who delivered Reed Richards's (Ioan Gruffudd) mail to him early in the movie.
Anthony Russo, Joe Russo: [Arrested Development (2003)] During the airport fight scene, a truck has the Bluth family logo. It is the same "stair car" (portable staircase for an airplane) that was the subject of many running jokes on Arrested Development. The Russo Brothers, the directors of this movie, also directed the pilot, and many other episodes of Arrested Development.