Audrey Hepburn's character was supposed to be thirteen when the movie begins. She was twenty-seven when this movie came out.
Henry Fonda later admitted he had known from the beginning that he was too old for his character, and had only made this movie for the money.
Marlon Brando was considered for the role of Pierre, but he did not want to work with Audrey Hepburn.
Audrey Hepburn's salary of three hundred fifty thousand dollars for this movie was the highest salary an actress had ever received to date. When notified of her record salary, Hepburn modestly told her agent, "I'm not worth it. It's impossible. Please don't tell anyone."
For the filming of the epic battle scenes, the producers hired sixty-five physicians, dressed them as soldiers and scattered them throughout the location to take care of any extras or stuntmen who might get injured during filming of the scenes.