The work on a Marvel Cinematic Universe (MCU) script is never really finished.
When speaking about MCU scripts, Marvel Studios President Kevin Feige said, "it's easy to stop, and it's easy to settle, and we don't do that."
"We never stop," Feige said during the NYFA Guest Speaker Series. "We work on the script during production. We work on the script in post. We work on the script throughout the entire process."
Feige credited the teams of people working on Marvel films for making the process of changing the script easier. "In order to do that, you need a couple of things: you need an amazing team around you, and you need to trust that team around you. You need that team to trust you."
Feige specifically mentioned the after-credits scene of 2012's The Avengers, in which all the heroes gathered at a restaurant for shawarma. According to Feige, this scene was thought of late in the cutting room and was filmed after The Avengers' official premiere.
Next up for Marvel Studios is the Black Widow solo film, which is being directed by Cate Shortland. Black Widow stars Scarlett Johansson as Natasha, Florence Pugh stars as Yelena, David Harbour as Alexei aka The Red Guardian, and Rachel Weisz as Melina. The film opens May 1, 2020.