Goofs

Blanche screws up the note to throw it to her neighbor. However, when Jane hands the folded note to Blanche it has no sign of having been screwed up. Apart from folded, the paper is pristine.

After Jane kicks Blanche, Blanche falls and Jane walks around her to kick her again, but when she kicks her again, she is in the same position that she was when she first kicked her, obviously as she kicks her from the right side of the screen (she would be on the left side of the screen if she walked around her).

Just prior to the scene where Mrs. Bates delivers flowers for Blanche, there was a short, deleted scene where a mailman brings a package for Blanche. Due to this, Blanche, mistaking says, "I was wondering who those PEOPLE where at the back door." (The package was full of fan letters, which Jane later reads, scribbles fowl notes on and then throws away.) The package is later found by Elvira in the trash and brought to Blanche.

In the first scene featuring nextdoor neighbor Mrs. Bates, she places the telephone on the coffee table twice.

Jane parks the Lincoln convertible in the garage front-first. The next time the car is seen, it's been backed into the garage.

If Blanche had been bound with her hands above her head and her upper body elevated above bed level, she would likely died of suffocation within a short time, especially in her weakened condition. Most victims of crucifixion died in a similar manner.

Blanche could simply shout to her neighbor through her open window. However, upon trying Blanche realizes her voice is simply too weak to carry far enough for the neighbor to hear her.

A graphic after the credits identifies the film's main narrative as beginning "Yesterday", though the events appear to take place over the course of several days and nights. However, it has been debated that "Yesterday" can merely be a synonym for "in the past".

Daddy Hudson announces that Baby Jane dolls can be purchased after the show and guarantees them to be exact duplicates of Baby Jane Hudson. The dolls in the foyer do not look like Baby Jane and are not identical to each other. However, it's clear that Daddy Hudson is just using sales talk in order to motivate people to buy the dolls.

In the end of the movie Baby Jane's mole does not appear on her cheek. This is intentional, as her "beauty mark" was drawn on with makeup all along. Note that it was heart-shaped for most of the film. The implication is that her makeup has rubbed off in that final, hectic day as she sweats on the beach.

When Edwin first visits the Hudson home, the wrought-iron gates at the front door swing inward as he enters. But later in the story, when he bursts out of the house after discovering what Jane has done to Blanche, the gates swing outward as he exits. Actually, those wrought iron gates are often on free-moving hinges that move in either direction, like a gate.

When Blanche is on the telephone after she has made her way down the railing (and right before Jane shuts the door, causing Blanche to realize that she has returned) her right leg moves, obviously voluntarily.

In the 1935 time line (11 minutes into the film), Ben Golden (Bert Freed) and Marty McDonald (Wesley Addy) are walking past a row of buildings in the studio discussing Baby Jane's acting. There are window air conditioners in almost every upper floor window of the 2-story building behind them. But the first window air conditioner wasn't marketed until 1938, and it wasn't until 1947 that they were mass-produced.

When Jane is checking her horoscope, she can be heard saying "Gemini", yet her mouth doesn't move.

During Baby Jane's performance of "I've Written a Letter to Daddy" in 1917, as Baby Jane and her father finish dancing in the far away shot, Baby Jane appears to continue singing before the audio begins.

When the neighbor catches Jane trying to leave in the car, Jane's voice does not match her mouth movements.

Jane's newspaper ad only gives the phone number. When she makes the appointment with Edwin she never mentions an address but he shows up anyway.

The police report describes Jane's car as a "1940 or 1941 black convertible." It is in fact a 1948 Lincoln Continental convertible.

When Mama Flagg dials the telephone in response to Jane's newspaper ad, she does not dial the number listed in the ad ("HO 5-6259"). In particular, the antepenultimate digit she dialed was not a two.