Audrey Hepburn hated Danish pastries, making filming the famous opening scene a bit of a chore for her.
Audrey Hepburn said the scene where she throws Cat into the rainy street was the most distasteful thing she ever had to do on film.
Audrey Hepburn supposedly exclaimed "over my dead body" when it was suggested that "Moon River" be removed from the film. However, there's an alternative recollection of this event. On the DVD of "Breakfast at Tiffany's Anniversary Edition," co-producer Richard Shepherd says in his commentary that after a premiere in San Francisco, Paramount's Head of Production desired to have "Moon River" removed from the film but "Marty Jurow, co-producer and I both said 'over our dead bodies.'"
Audrey Hepburn's salary for the film was $750,000, making her the second highest paid actress (behind Elizabeth Taylor) per film at the time.
Steve McQueen was offered the co-starring role. However, he was still under contract for the show Wanted: Dead or Alive, which prevented him from appearing. The role eventually went to George Peppard.
George Peppard was a student of Method acting, a style Hepburn found difficult to work with. Nonetheless, the two actors remained close friends until her death.
Alan Reed, who plays Sally Tomatoes, was the voice of Fred Flinstone, a Hanna-Barbera cartoon. Huckleberry Hound - the mask that Holly picks up in the store - is also a Hanna-Barbera cartoon.
John Frankenheimer was hired to shoot the film with Marilyn Monroe. When the producers suddenly moved to Switzerland and Audrey Hepburn replaced Monroe, she said she had never heard of Frankenheimer and insisted that he be paid off and another director be hired.
Jean Seberg was considered to play Holly.
Truman Capote maintained that he based Holly Golightly on Carol Grace (the former wife of William Saroyan and future wife of Walter Matthau), who had been a friend of his while living in New York.
Truman Capote was reportedly unhappy with the decision to cast Audrey Hepburn as he'd been in favor of Marilyn Monroe. Hepburn was very self-conscious of her performance while Capote was on set as she felt inadequate as the Holly he had envisioned.
Henry Mancini wrote "Moon River" specifically for Audrey Hepburn. He later said that while many version of the song have been done, he feels that Audrey's was the best.
2-E (Patricia Neal's character) references Love Finds Andy Hardy, in which Mickey Rooney played the title role.
About nine cats were used throughout the film as the role of Cat.
According to the screenplay, 2-E's real name is Emily Eustace, hence the nickname "2-E."
After seeing Buddy Ebsen in his country role in Breakfast at Tiffany's, the creator of The Beverly Hillbillies wanted him to play family patriarch Jed Clampett. At the time, Ebsen was thinking of retiring, but the producers sent him a copy of the script, and he changed his mind.
Although it's never explained why Holly is wearing a bed sheet at her cocktail party, an earlier scene (cut before release) established she'd been taking a bath and had to improvise a gown on the spur of moment. The cut scene was featured in Life magazine pictorial shortly before film was released.
Although not visible on camera, hundreds of onlookers watched Audrey Hepburn's window-shopping scene at the start of the film. This made her nervous and she kept making mistakes. It wasn't until a crew member nearly got electrocuted behind the camera that she pulled herself together and finished the scene.
Although the story in the movie occurs in 1960, the story in the novella is penned as occuring in 1943.