https://en.wikipedia.org/wiki/Captain_America:_Civil_War#Cast
Paul Rudd as Scott Lang / Ant-Man:
A former petty criminal allied with Captain America, who acquired a suit that allows him to shrink in scale but increase in strength. Ant-Man director Peyton Reed revealed that he had discussed the character and the way that the Ant-Man production had shot certain sequences with the Russo brothers, saying, "As we were doing the movie and we were in post and they were getting ready to head out to Atlanta to do Civil War, we had a lot of conversations. And I actually wanted those guys to come in and look at our stuff, because there’s gotta be a lot of sort of crossover. I found myself getting extremely protective over the character of Scott Lang and talking to the guys, the writers, the Russo’s about, He wouldnt do that. It’s important because there’s this continuity that has to happen in this universe."