During the attack scene according to the script, Grace Kelly was to get out of bed, put her robe on, and answer the phone when it rang. Grace Kelly contended that no woman, being at home, would put a robe on to answer the phone. Alfred Hitchcock agreed, and so the scene was shot with her in her nightgown.
Warner Brothers insisted on shooting the movie in 3-D although the craze was fading and Alfred Hitchcock was sure the movie would be released flat. The director wanted the first shot to be that of a close-up of a finger dialing the letter M on a rotary phone, but the 3-D camera would not be able to focus such a close-up correctly. Hitchcock ordered a giant finger made from wood with a proportionally large dial built in order to achieve the effect.
Alfred Hitchcock had chosen a very expensive robe for Grace Kelly to wear when she answered the phone. The actress balked and said that no woman would put a robe on to answer the phone when she was sleeping alone but would answer it in her slip. Hitchcock agreed to do it her way and liked the way the rushes turned out. The director agreed to allow the actress to make all costume decisions for herself in their subsequent films together.
Filmed in 3D, which explains the prevalence of low-angle shots with lamps and other objects between us and the cast members. There was only a brief original release in 3D, followed by a conventional, "flat" release; The New York Times review mentioned it opened with the "flat" release at the Paramount in New York. The 3D version was reissued in 1980.
In a television interview Ray Milland said that he had fluffed his lines in a particular scene in the movie and ruefully apologized to the director. Alfred Hitchcock, he said, stared at him stonily for few seconds and then said: "I wound it up, put it on the floor, and it wouldn't go."
Adapted from a Broadway play that opened at the Plymouth Theater in New York on October 29, 1952 and ran for 552 performances. In the original production, Maurice Evans played Tony Wendice. In this film, John Williams and Anthony Dawson recreate their stage roles of Chief Inspector Hubbard and Captain Lesgate. J. Pat O'Malley later replaced Williams as Hubbard.
At their first meeting, the untrustworthy Captain Swann is wearing a tie the colours of a Guards regimental tie. However this is not a genuine tie, as the diagonal stripes run in the American direction, opposite to British style. This is a contemporary detail, used by spivs. The tie resembles the trustworthy Guards tie well enough to fool most, but gives an excuse if a genuine Guardsman queries one's service record.
The trivia items below may give away important plot points.
After several unsuccessful attempts to film the scene where Margot stabs Swan with the scissors, Alfred Hitchcock said, "This is nicely done but there wasn't enough gleam to the scissors, and a murder without gleaming scissors is like asparagus without the hollandaise sauce - tasteless."