Redford Actually Wanted to Do His Own Stunts
Robert Redford was the new kid in town, but boy did he have ambition. He reportedly wanted to do all of his own stunts in the movie, particularly the stunt where Sundance jumps on top of a moving train and runs along the top as it moves. This, apparently, was very upsetting to Newman. He wasn’t upset because Redford was trying to show off or anything.
Newman was concerned about his co-star’s safety. Redford later recalled what Newman told him: “I don’t want any heroics around here. I don’t want to lose a co-star.” In the end, Redford left the life-threatening stunts to the professionals. As for the non-threatening ones, both Newman and Redford performed many of them.