The drive-in cinema scene takes place at night, yet when K.I.T.T. turbo-boots through the movie screen, the "undercarriage" shot shows bright blue sky.
Norman Baines has a large leather-sheathed boot-knife as he carries the sack of pumpkins up the steps of his apartment-complex, yet when he walks into his room, he's just wearing his plain-cuffed pants.
Ms. Barstow tries to find the keys for a door with a lock in the knob. In the next shot, there is a handle and a separate lock.
Lizzie Borden was never actually convicted (nor even definitively suspected by the courts) of axing her parents to death (it was later thought by some that a male miscreant family member was more likely the true culprit), so Michael's alluding to her as an example of a innocent-looking-lady-turned-murderer was not really valid, especially since it is still widely believed that Miss Borden was indeed innocent, just as she'd always claimed to be.
A hologram projector is used to make Ms. Barstow think that she is hallucinating. Even as of 2020, holograms cannot be projected into thin air.
When Michael tackles Simon at the drive-in at the end, it's an obvious stunt double for Michael.
Bonnie claims that the now-empty apartment was furnished (she even describes specific details, such as wall-hangings, a lamp, etc.), yet she had an extremely "narrow" view from a great distance and through two sets of windows that merely showed the gorilla-suited guy and the lady he was roughing up, so there were virtually no other details of the apartment's "surroundings" visible. Bonnie also says that the woman "knocked over a lamp as she fell", yet no lamp or other objects are visible through the windows as the lady falls over.
The cameraman is visible in the right-hand side of the mirror during the hologram scene.