Exterior shots of the Hudson house were filmed at 172 S. McCadden Pl. in Los Angeles. Right next door at 180 S. McCadden Pl. is the house Judy Garland lived in during production of The Wizard of Oz (1939).
Bette Davis had been nominated for Best Actress in her film What Ever Happened to Baby Jane? (1962), which also starring Joan Crawford. If Bette had won, it would have set a record number of wins for an actress. According to the book "Bette & Joan - The Divine Feud" by Shaun Considine, the two had a life long mutual hatred, and a jealous Joan Crawford actively campaigned against Bette Davis for winning Best Actress, and even told Anne Bancroft that if Anne won and was unable to accept the Award, Joan would be happy to accept it on her behalf. According to the book - and this may or may not be 100% true, but it makes a good anecdote - on Oscar night, Bette Davis was standing in the wings of the theatre waiting to hear the name of the winner. When it was announced that Anne Bancroft had won Best Actress for The Miracle Worker (1962), Bette Davis felt an icy hand on her shoulder as Joan Crawford said "Excuse me, I have an Oscar to accept".
In her book "This N' That", Bette Davis said she had a lot of control over how her makeup should be done for the film. She imagined the older Jane as someone who would never wash her face, just put on another layer of makeup. When her daughter, Barbara Merrill, first saw her in full "Jane" makeup, she said, "Oh, mother, this time you've gone too far".
While touring the talk show circuit to promote the movie, Bette Davis told one interviewer that when she and Joan Crawford were first suggested for the leads in this film, Warner Bros. studio head Jack L. Warner replied: "I wouldn't give a plugged nickel for either one of those two old broads." Recalling the story, Davis laughed at her own expense. The following day, she reportedly received a telegram from Crawford: "In future, please do not refer to me as an old broad!"
Because she was then a member of the Pepsi-Cola board of directors, Joan Crawford managed to see that product placement shots of the soft drinks appeared in all of her later films. Although nearly imperceptible, Pepsi does show up in this one. During the last sequence, a guy runs up to the refreshment stand on the beach and tries to collect the deposit on some empty Pepsi bottles - a transaction that actually only happened in stores.
Joan Crawford was an avid collector of Margaret and Walter Keane's "sad eyes" paintings and befriended the couple and tried to incorporate their work into her films. In the film, during the interior scenes of the neighbor's (Mrs. Bates) house, several Keene paintings can be seen displayed on the walls.
Cracked head of Baby Jane doll featured prominently in ad campaign was a completely different doll than that used in movie - probably because movie was filmed and released so quickly that ad staff had to devise campaign while film was still in production.
In addition to her trademark number "I've Written a Letter to Daddy", the young Baby Jane apparently had other hit songs in her act. When Edwin prepares to play the piano for their rehearsal, we see Jane's picture featured on old sheet music for songs entitled "Fly the Flag of Freedom", "She's Somebody's Little Girl", and "I Wouldn't Trade My Daddy".
This film is considered by many as Joan Crawford's last important picture. After this film, Joan was typecast in some lesser horror pictures until her last picture Trog (1970) in 1970 and some TV appearances in 1971 and 1972.
It takes a while for both leads to appear on screen, with Joan Crawford appearing first while watching her character's old picture. Bette Davis finally appears about a minute later, and by this point, it's nearly 20 minutes into the picture.
Peter Lawford was originally set to play the part of Edwin Flagg but two days after accepting the part he withdrew due to family concerns. Lawford felt the character might reflect badly on his real life role as brother-in-law of the current President, John F. Kennedy. Victor Buono was then cast as Edwin. Bette Davis originally objected to Buono's casting but eventually came around.
Actor Bill Walker appeared in a deleted scene delivering a package to Jane at the Hudson Mansion. It was filmed in the studio recreation of the house but never made it to the final release. He is uncredited.