Three Black Widows on Set
Scarlett Johansson was pregnant while shooting this, so the crew front-loaded a lot of her scenes early in production before it started to show and brought in three separate stunt doubles for the physical stuff later on. The doubles apparently looked so much like her that even her co-stars got confused, with Chris Evans admitting he'd sometimes start chatting to one of them mid-scene before realising it wasn't Scarlett at all.
