Continuity: The break on the driver's side of the windshield of Grisby's car vanishes.
Continuity: Narrator mentions they arrive back in San Francisco on early-October, but in the document (prepared by Grisby) that Wells signs verifying his killing of Grisby, it is dated August 9th, supposedly the next day.
Continuity: Rita dives off the cliffs. However, in the following scene as she boards the boat her hair is dry.
Audio/visual unsynchronized: In the Crazy House, Mrs. Bannister's lips do not match the line "we could have gone off together."
Revealing mistakes: When Mrs. Bannister is lunging for the exit in the mirrored room, the "broken glass" in the foreground stays in frame as the camera pans to the right, spoiling the illusion of a cracked window.
Errors made by characters (possibly deliberate errors by the filmmakers): Elsa spent time in Shanghai, which has its own dialect. But in Chinatown she switches between Mandarin and Cantonese.