The stunt where the man crawled under the carousel was not done with trick photography. Alfred Hitchcock claimed that this was the most dangerous stunt ever performed under his direction, and would never allow it to be done again.
Alfred Hitchcock and Robert Walker worked out an elaborate series of gestures and physical appearance to suggest the homosexuality and seductiveness of Bruno's character while bypassing censor objections.
This is the movie that determined the location of Carol Burnett's star on the Hollywood Walk of Fame. In 1951, she was working as an usher when this film was playing at the Warner Theatre on Hollywood Blvd. A couple arrived late, and Burnett, having already seen the film, advised them that it was a wonderful film that should be seen from the very beginning. The manager of the theatre very rudely fired her for this. Years later, when Carol Burnett was asked where she would like to have her star placed on the Hollywood Walk of Fame, she requested that it be placed in front of that theatre.
Alfred Hitchcock had admired Edgar Allan Poe's stories since his teenage years, and went on to put Edgar Allan Poe references in his films. French critics noticed that there are connections between the runaway carousel in this film and Poe's "A Descent into the Maelstrom".
The final scene of the so-called American version of the film has Barbara and Anne Morton waiting for Guy to call on the telephone. Alfred Hitchcock wanted the phone in the foreground to dominate the shot, emphasizing the importance of the call, but the limited depth-of-field of contemporary motion picture lenses made it difficult to get both phone and women in focus. So Hitchcock had an oversized phone constructed and placed in the foreground. Anne reaches for the big phone, but actually answers a regular one: "I did that on one take", Hitchcock explained, "by moving in on Anne so that the big phone went out of the frame as she reached for it. Then a grip put a normal-sized phone on the table, where she picked it up."
In an interview, Farley Granger revealed that this film and They Live by Night (1948) were his favourite films. Granger also revealed that he loved working with Robert Walker and was very upset when he heard about Walker's sudden death which happened a couple of months after the shooting of this film.
The relationship between Raymond Chandler and Alfred Hitchcock was not a happy one. The main bone of contention between the two men was that Chandler's writing paid more attention to character motivation while Hitchcock was more interested in the visual development and formal structure of the movie laid out in the treatment. In a letter to a studio executive, Chandler said he preferred to work with a director "who realizes that what is said and how it is said is more important than shooting it upside down through a glass of champagne." The two men also had different meeting styles. Hitchcock enjoyed long, rambling off-topic meetings where often the film would not even be mentioned for hours, while Chandler was strictly business and wanted to get out and get writing. He called the meetings "god-awful jabber sessions which seem to be an inevitable although painful part of the picture business." Chandler was also a hard drinker and a difficult person to get along with under the best of circumstances. Interpersonal relations deteriorated rapidly until finally Chandler became openly combative. When Hitchcock arrived at Chandler's home for a story meeting, Chandler hollered from his window, "Look at the fat bastard trying to get out of his car!" When his secretary warned that Hitchcock might be able to hear him, Chandler said he didn't care.
Patricia Hitchcock was encouraged by her father to go for a ride on the Ferris wheel constructed on the fairgrounds set. In exchange for doing it he offered her $100 because she did not want to do it as she is scared of heights. She was finally persuaded to do it partly for the money. When she reached the top, Alfred Hitchcock ordered the ride stopped and all lights turned out for something like five seconds. She never got the money and calls her father's act "sadistic."
According to Farley Granger, Alfred Hitchcock hated Ruth Roman and treated her very harshly, often criticizing her in front of everyone. "He had to have one person in each film he could harass," Granger noted.
According to Farley Granger, Alfred Hitchcock, who worked all his shots out in great detail on paper before shooting, often looked unhappy on the set. When the actor asked him if something was wrong, Hitchcock complained, "Oh, I'm so bored!"
Alfred Hitchcock refused to treat his daughter preferentially, which won them both the respect of the other players. "We never discuss Strangers on a Train at home," she told an interviewer at the time. "On the set, he gives me direction as well as criticism. I might as well be Jane Jones instead of Patricia Hitchcock."
An amusement park was created according to Alfred Hitchcock's exact specifications at the ranch of director Rowland V. Lee in the Los Angeles suburb of Chatsworth. However, the tunnel-of-love scenes were shot at a fairground in Canoga Park.
The merry-go-round scene is not in the book, but is taken from the climax of Edmund Crispin's 1946 novel The Moving Toyshop.; All the major elements of the scene - the two men struggling, the accidentally shot attendant, the out-of-control merry-go-round, the crawling under the moving merry-go-round to disable it - are present in Crispin's account, though he received no screen credit for it.
When the movie was released in Germany in 1952, about five minutes were removed which were considered too brutal or sadistic. Later the scenes were re-added for TV, but they are subtitled, while the rest of the movie is dubbed.
There were several changes made from the original novel: the character Bruno Antony was named Charles Anthony Bruno and Guy Haines was an architect, not a tennis player. Also, Anne Morton was originally named Anne Faulkner.
While the script was still being worked on, Alfred Hitchcock went to the Forest Hills tennis club in New York to film the Davis Cup matches between Australia and the U.S. for long shots of Guy competing.
As Guy leaves the last match, part of a quotation clearly including the words "two impostors" is visible on the beam above his head. It is from Rudyard Kipling's poem "If." The line reads "If you can meet with triumph and disaster / And treat those two impostors just the same..." It appears above the players' entrance at Wimbledon's Centre Court
Alfred Hitchcock wanted a "name" writer to lend some prestige to the screenplay, but was turned down by eight writers, including John Steinbeck and Thornton Wilder, all of whom thought the story too tawdry and were put off by Patricia Highsmith's first-timer status. Talks with Dashiell Hammett got further, but here too communications ultimately broke down, and Hammett never took the assignment.
Warner Bros. wanted their own stars, already under contract, cast wherever possible. In the casting of Anne Morton, Jack L. Warner got what he wanted when he assigned Ruth Roman to the project, over Alfred Hitchcock's objections. The director found her "bristling" and "lacking in sex appeal" and said that she had been "foisted upon him."
Kasey Rogers noted that she had perfect vision at the time the movie was made, but Alfred Hitchcock insisted she wear the character's thick eyeglasses, even in long shots when regular glass lenses would have been undetectable. Rogers was effectively blind with the glasses on, and needed to be guided by the other actors. In one scene, she can be seen dragging her hand along a table as she walks; this was in order for her to keep track of where she was.
Cinematographer Robert Burks began an association with Alfred Hitchcock on this picture that would last another 13 years and a dozen films. "You never have any trouble with him as long as you know your job and do it," Burks said. "Hitchcock insists on perfection. He has no patience with mediocrity on the set or at a dinner table. There can be no compromise in his work, his food, or his wines."
Similar to the scene of Bruno at the Morton's party, Alfred Hitchcock enjoyed showing people in social situations how to strangle someone. Also, a famous sequence of photos by Philippe Halsman shows Hitchcock doing various things to a bust of his daughter, including strangling her.
In the scene where Ruth Roman and Patricia Hitchcock are watching the tennis match, Ruth gives Patricia a real United States ten dollar bill. Showing real US money in films then was illegal without permission from the US Treasury Department. The Treasury Department later removed the prohibition for the film "Psycho" and later films.
The scene of the climactic fight on the carousel and the ride's subsequent explosion was very complicated to shoot with a combination of live action and rear screen projection. It usually took about a half day to set up each shot so the actors and the projected image matched.
Patricia Highsmith's opinion of the film varied over time. She initially praised it, writing: "I am pleased in general. Especially with Bruno, who held the movie together as he did the book." Later in life, while still praising Robert Walker's performance as Bruno, she criticized the casting of Ruth Roman as Anne, Alfred Hitchcock's decision to turn Guy from an architect into a tennis player, and the fact that Guy does not murder Bruno's father as he does in the novel.
The film did not initially end with Guy Haines and Anne Morton on the train. In another version of the film it ends just before this. This other reel was mistakenly labeled 'the British version' leading people to believe that this was what was shown in Britain. This is in fact incorrect and the same ending was broadcast in Britain and America.