For the filming of the epic battle scenes, the producers hired 65 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.
Jeremy Brett was chosen to play Nicholas in part because it was felt he resembled his on-screen sibling, Audrey Hepburn.
Audrey Hepburn's salary of $350,000 for the film 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."
The first draft of the screenplay was 506 pages, over 5 times the size of an average screenplay.
In the scene where the Rostovs invite Prince Andrei to go hunting with them, Jeremy Brett is the only actor never on a mechanical horse: in all his shots he is clearly on a live horse. Audrey Hepburn, Henry Fonda, Mel Ferrer, Barry Jones and May Britt are all clearly on mechanical horses in their close shots.