Trivia

The opening model shot of London was huge, 50 feet by 70 feet in size, and made of plaster. It took four months to construct.

Because wartime rationing made supplies of metal scarce, all the chain-mail armor in the movie was made of hand knitted grey wool.

As a tribute to his abilities as a director, and uncertain over his own unproved directing abilities, Sir Laurence Olivier originally invited William Wyler, who had directed him in Wuthering Heights (1939), to direct. It was Wyler who Olivier always credited with teaching him how to give a more subtle performance in movies, and with giving him more respect for the art of acting in movies. Wyler, however, declined, saying, "If it's William Shakespeare, it must be you" who directs the movie. Sir Carol Reed and Sir Ralph Richardson told him the same thing.

Sir Laurence Olivier's then wife, Vivien Leigh, very much wanted to play Katherine, but David O. Selznick would not let her out of her contract with Selznick International Pictures, feeling that the role was much too small for an actress of her cache. Leigh never forgave Selznick, and never worked for him again.

The filming of a battle scene was stopped in order for the company to watch, while overhead, a group of British fighters attacked a formation of German bombers on their way to bomb London. When the real battle passed out of sight, the movie battle resumed filming.