According to Bette Davis in her book "This N' That," the film was originally going to be shot in color. Davis opposed this, saying that it would just make a sad story look pretty.
Bette Davis and Joan Crawford worked hard to promote the film, both knowing that their profit percentage points would pay off in spades with the film's success. Davis traveled to 17 theaters across the state of New York in three days for personal appearances and helped give away promotional "Baby Jane" dolls to patrons with a "lucky envelope" under their seat.
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."
The budget was so limited that the production wasn't able to use the usual process screen shots for Jane's driving scenes. Bette Davis did her own driving around Hollywood with cameraman Ernest Haller perched either in the back seat of the car or over the front fender in order to get the shots he needed. "To this day," said Davis in 1987, "I smile when I remember the first time 'Jane' drove down Beverly Boulevard in an old Hudson. The expressions on the faces of people in other cars when they saw me were hysterical. Lots of mouths dropped."
Early on, Bette Davis made the decision to create her own makeup for Jane. "What I had in mind no professional makeup man would have dared to put on me," said Davis. "One told me he was afraid that if he did what I wanted, he might never work again. Jane looked like many women one sees on Hollywood Boulevard. In fact author Henry Farrell patterned the character of Jane after these women. One would presume by the way they looked that they once were actresses, and were now unemployed. I felt Jane never washed her face, just added another layer of makeup each day." Davis' garish makeup made her look something akin to a grotesque version of an aging Mary Pickford gone to seed, and she loved it. She took pride when Farrell visited the set one day and exclaimed, "My God, you look just exactly as I pictured Baby Jane." The outrageousness of Davis' appearance caused some concern for Aldrich and the producers, who feared it might be too over-the-top. However, as time went on, they came to see that Davis' instincts for the character were right.
Barbara Merrill: The curious teenager who lives next door to the Hudson sisters is Bette Davis' real-life daughter.
Robert Aldrich: [necktie] Early in the film Bert Freed, playing a film director, can be seen wearing a necktie that's not tied in a knot but is instead crossed over and held on by a tie clasp, as Aldrich always did.