Ant-Man DVD: 10 Things We Learned From Director's Commentary

7. The Studio Wondered Why Scott Put On The Suit Too

The scene after Scott completes his heist of Pym's residence, where he puts on the Ant-Man suit seemingly just... because, is a baffling moment. It's simply necessary on the part of the film to get him into the suit, so that he can experience what it can do and have his trial by fire ("or in this case... water"), but there's no real explanation in the film. Rudd tells an interesting anecdote regarding the scene; himself and McKay actually received notes from the studio asking why Scott would put on the suit for no good reason, to which Rudd replied... "Why wouldn't he?". Which is fair enough. Rudd and Reed also discuss how they did additional takes of Scott in the suit, talking into the bathroom mirror, doing impressions of Robert De Niro in Taxi Driver (you know the scene), and C-3PO, inspired by the retro look of the suit. The latter of which I would pay good money to see.