Over the years in the Marvel Cinematic Universe, we’ve certainly learned there’s no single role, no matter how small, that is restricted to the movie an actor is cast in. Heck, Gwyneth Paltrow signed on for the Iron Man movies and famously forgot she showed up in a Spider-Man movie. Over the past decade, Marvel has done all kinds of sneaky things to keep all its films interconnected.
Article source: https://www.cinemablend.com/news/2553392/looks-like-ant-man-was-going-to-feature-a-key-iron-man-3-character