Trivia: The Chinese extras cast in this film were almost all Spanish residents, especially in Madrid. This was done to such an extreme extent that some Chinese restaurants and other Chinese-Spanish-owned businesses in the Madrid area especially were forced to close for a few days due to lack of personnel.
Trivia: Fay Compton and Michael Redgrave play mother and son in this film. In real life, Compton was only thirteen years older than Redgrave.
Trivia: In this rather clunking classic murder mystery, the closing gimmick of the film is a sequence of several otherwise unremarkable supporting characters grandly removing their heavy latex makeup to reveal A-List Hollywood movie stars who played mundane roles in the film. The heavily-disguised stars in this film include Kirk Douglas, Tony Curtis, Robert Mitchum, Burt Lancaster and Frank Sinatra. Director John Huston (who also made a cameo appearance in the film) tried to convince Elizabeth Taylor to play a disguised part in this movie, as well; but, when Taylor learned that her lovely face would be completely hidden under heavy latex, she turned down the role.
Trivia: Ron Moody was only 4 years older than Bernard Cribbins, who plays his son.
Trivia: Julie Harris was very aloof during filming and would often ignore her co-stars behind the scenes - especially Claire Bloom. Bloom felt very hurt by this. However, after filming, Harris showed up at Bloom's house with a gift and revealed that she actually really liked Bloom and her other co-stars. She behaved as she did during filming because she was trying to stay in-character between takes, and was worried that her performance as an outsider would suffer if she was friendly with her co-stars.
Trivia: Patricia Neal won the Academy Award for Best Actress for her role as Alma Brown, even though she's only on screen for a total of 21 minutes and 51 seconds. This is the shortest performance ever to win the Award.
Trivia: The film was to have run six hours with two intermissions, but it was cut down to four with one.