Continuity mistake: Immediately after the (Dali) dream sequence, when Dr. Brulov and Constance are reviewing Constance's notes, Dr. Brulov draws a pencil out of his coat pocket. Hitchcock then cuts to a close-up, and Dr. Brulov repeats the motion.
Continuity mistake: After the raid on the Japanese radar site as Errol Flynn is on the radio sitting next to a radioman talking to the supply plane his hair is sweaty and forming circles on his forehead. When the scene shifts to a close-up of Errol his hair is in straight lines.Then when the scene goes back to the two of them his hair is in circles again.
Continuity mistake: Even though the heavy rain had only just stopped, as Laura sits alone on the bench, the pavements around her are completely dry.
Continuity mistake: The dead body Wally discovers in the house has its head straight in the long shots, but canted to the right in the close ups.
Continuity mistake: Blore, Lombard and Armstrong get out of the house to check on the knocking noise. As they stare at the door of the shed that keeps slamming in the wind, their reciprocal distance greatly varies; they are closely together, then Armstrong is at distance - to allow the camera to get a better shot -, then he is touching shoulders with Lombard. (00:52:30)
Continuity mistake: Doctor Leo sits at the desk and begins writing a letter to Alec Ritchfield. "My dear Alec", it starts. Fade to the finished letter, but you can easily tell that it's not the same letter, the handwriting being different - look at the little flourish below the M, not to mention the position of the text in relation with the Fog Island stamp. (00:08:25)