Diane Baker has said that for the scene where she eavesdrops on Mark and Marnie talking outside of the house, Alfred Hitchcock came up to her, put his hands on her face, and physically manipulated it into having the expression he wanted for the scene.
After rehearsing just a few scenes with co-star Sean Connery, Tippi Hedren asked Alfred Hitchcock, "Marnie is supposed to be frigid - have you seen him?" referring to the young Connery. Hitchcock's reply was reportedly, "Yes, my dear, it's called acting."
To film real horses riding without having to work outdoors, Alfred Hitchcock came up with the idea of running the horses on a gigantic treadmill. Crew members objected to the idea because it was considered highly unsafe and because they simply didn't think it would work. Still, Hitchcock wanted to at least try it, and when they did, it worked without a problem. Originally, a harness was attached to Tippi Hedren during these shots for safety reasons, but it was removed when it was found to impede shooting.
Alfred Hitchcock first asked Evan Hunter, the screenwriter for The Birds (1963), to adapt the novel after Tippi Hedren had signed on. However, Hunter strongly objected to the scene in the novel where Mark rapes Marnie, as he felt it was "unheroic" and that it would make women in the audience hate Mark. When he pressed Hitchcock about changing the scene, Hitchcock fired him. Jay Presson Allen, who took over as screenwriter, stated that opposition to the rape scene doomed Hunter since that scene was the main reason Hitchcock wanted to do the film. For her part, Allen said she never had any qualms about including the scene, and felt it was up to Sean Connery and his charisma to make the audience "forgive" Mark's actions.
Joseph Stefano originally wrote a screen adaptation of the novel when Grace Kelly was supposed to star. Stefano's adaptation was much truer to the original book, and would have included two important characters from the novel that never made it into the final version of the film. One was a psychotherapist that Marnie was seeing at Mark's insistence, whose role ended up being merged into Mark's. The other was a man named Terry who was a co-worker of Mark's and also in love with Marnie. The part of Terry was massively reworked and ended up becoming Lil.
Alfred Hitchcock and Tippi Hedren had a major falling-out during the filming and there was a rumor that by the end he directed her through intermediaries. Although Hedren admits the she and Hitchcock's friendship ended during shooting, she denies the rumor that he didn't finish directing the film.
When Alfred Hitchcock's discussion with Grace Kelly (to appear as the title character) became public, the residents of Monaco expressed their disapproval, and Kelly withdrew. In a further complication, since Kelly had not fulfilled her MGM contract when she married Prince Rainier of Monaco in 1956, she could not appear in any film other than an MGM film until she fulfilled the terms of her MGM contract.
The 6 & 1/2 carat blue-white flawless diamond ring that Mark buys for Marnie cost $42,000, or approximately $285,000 in 2008 currency, when factored for inflation. In the week that Mark had returned with Marnie up until their marriage, he spends approximately $70,000, including the ring, or approximately $475,000 when factored for inflation.
Alfred Hitchcock and screenwriter Jay Presson Allen were allowed to see scenes from Dr. No (1962) when considering Sean Connery for the role of Mark. They liked his charismatic performance so much that they decided to offer him the role even though the obviously Scottish actor did not really fit with their conception of Mark as an "American aristocrat."
Tippi Hedren has stated that many people have asked her what it was like to kiss the handsome Sean Connery in this film. Her reply was, "How sexy was it? It wasn't. It was simply technical. It was totally technical."
Actress Naomi Watts dressed up as "Marnie" for a portrait that was published in the March 2008 issue of the magazine "Vanity Fair." (She said she was fascinated by Tippi Hedren when they both acted in the film I Heart Huckabees (2004).
Marnie arrives in Philadelphia on Saturday, November 30, 1963 which can be determined by the copy of the Philadelphia Inquirer she is carrying as she exits 30th Street Station. This issue of the Inquirer, which was published four days after filming for the movie began on November 26, has the headline "Crash Kills 118" which refers to Trans-Canada Air Lines (TCA) Flight 831 from Montreal to Toronto, a DC-8-54CF which crashed at 6:33PM on November 29, 1963 about five minutes after takeoff from Dorval Airport killing all 111 passengers and 7 crew. The other headline starting "President Picks" refers to the establishment of the Warren Commission by President Johnson on November 29 to investigate the assassination of President Kennedy in Dallas one week earlier on November 22.
Alfred Hitchcock, following his usual practice, bid for the film rights to Winston Graham's novel anonymously, so as to keep the price down. However, in this instance, the scheme backfired - the anonymity of the purchaser made Graham suspicious, although he regarded the amount of money on offer as extremely generous. He instructed his agent to ask for twice as much. Hitchcock agreed, on condition that the deal be closed immediately. When Graham discovered who it was who had bought the rights, he said he would have given them away free for the honor of having one of his stories filmed by Alfred Hitchcock.
Screenwriter Jay Presson Allen thought that the expensive car Mark drove and the fancy clothes worn by his father were ridiculous and out of place, but Alfred Hitchcock insisted that they were necessary to convey the proper feeling of Mark being part of an "American aristocracy" to the audience.
Alfred Hitchcock was loathe to use a mechanical horse to film the shots of Marnie riding, but sent a crew member to inspect a mechanical horse owned by Disney that was supposed to be the best in existence. Walt Disney spotted the crew member on the Disney lot and personally offered to let Hitchcock use it, which he did.
The trivia item below may give away important plot points.
Alfred Hitchcock put Edgar Allan Poe references throughout this film. Marnie's last name is Edgar. In the novel, Marnie's last name is Elmer. Unlike the film, the novel takes place in England. Like Poe's characters, Marnie Edgar is subject to Psychological terror. The film takes place in New York (Strutt's office), Virginia (Garrod's Stables) and Philadelphia (Rutland Publishing and Wickwind). These are the three places that Edgar Allan Poe lived throughout the better part of his life. The film's climactic scene takes place at Marnie's mother's home in Baltimore, the city where Poe died under mysterious circumstances in 1849. Tippi Hedren played Marnie. Both Tippi Hedren and Edgar Allan Poe were born on January 19. In the novel, Marnie's mother's name is Edith Elmer. In the film, Alfred Hitchcock changed Marnie's mother's name to Bernice Edgar. "Berenice" was a short story written by Edgar Allan Poe. In a 1960 article called "Why I Am Afraid of the Dark", Hitchcock noted this information - "...it's because I liked Edgar Allan Poe's stories so much that I began to make suspense films."