"In Lord of the Rings: The Two Towers when Aragon, Gimli, and Legolas are approaching the pile of smoldering and dismembered corpses looking for Pipin and Mary, Vigo Mortensen kicks a helmeted Orc head and screams, thinking the hobbits are dead and gone.
It's a really good scream and 100% authentic. When Mortensen kicked the head/helmet he broke two of his toes. He used the pain and stayed in character. They kept the scene for the movie."
"In avengers, Robert Downey Jr would hide food around the sets and eat them while filming. The crew would attempt to find his stashes but never(?) did. All those times he was eating on screen were unscripted."
https://www.imdb.com/name/nm0778734/