Harvey Keitel

Despite not being the director’s first choice, the casting team hired Harvey Keitel to play the role of Captain Benjamin L.Williard in Apocalypse Now. Unhappy with his portrayal of the character, the director called his first pick, Martin Sheen, to play the part. At first, Sheen couldn’t take up the part due to scheduling conflicts, but later, he took the job and played his role with the passive feeling that the director envisioned.
Julianne Moore

Due to a conflict in opinion, the director of Can You Ever Forgive Me? let go of Julliane Moore just six days before production began. Moore reportedly said, “I think that her idea of where the character was, was different than where my idea of where the character was.” Moore wanted to wear a fat suit to make her character look more realistic. Since the director disagreed, he replaced Moore with Melissa McCarthy. Lucky for McCarthy, the role landed her in being nominated for the Best Actress Academy Award.
Jean-Claude Van Damme

Before Kevin Peter Hall was appointed, there was a great chance that Jean-Claude Van Damme would’ve played the part of the feared hunter. The reason for his replacement is unknown. However, one of the known reasons is the heavy costume and prosthetic makeup he had to wear. Crew members reportedly said that he once fainted on set as he couldn’t breathe in the costume.