Continuity mistake: When Marion and Norman are talking after he has brought in some sandwiches, Marion tears the same piece of bread 3 times on different occasions.
Continuity mistake: When Marion steps into the shower, we can hear (not see) her unwrap a bar of soap and throw the wrapper on the floor of the shower. But when Norman is cleaning the bathtub, after Marion is killed, the wrapper is no where in sight. (00:46:30 - 00:53:00)
Continuity mistake: When Marion arrives at the Bates motel, she sounds the car horn for the first time, the windscreen wipers are switched on. She gets out of the car, looks towards the old house, then goes back to the car, as she sounds the horn for the second time the windscreen wipers are now switched off.
Continuity mistake: As the camera zooms into the hotel window, you can see a shadow on the blinds. But in the next shot, the shadow is now longer (even though it's supposed to be in real time). (00:02:30)
Continuity mistake: In the shot in which Norman goes into the bathroom and puts the pail behind the door, the shower curtain rings are spread out. In the very next shot in which he emerges from behind the door, the rings are in tight groups. As he leaves the bathroom, the rings are spread out again.
Continuity mistake: When Mother Bates leaves the motel room after stabbing Marion, she leaves the room door wide open. When Norman reaches the door to check on Marion, the door is closed.
Continuity mistake: After seeing Marion's dead body in the bathroom, Norman accidentally knocks down a framed picture of a bird (with the picture facing up and it is a few inches away from the wall). But when Norman is spreading the shower curtain on the floor, the picture has changed position (with the picture now facing down and it is against the wall). (00:49:50 - 00:51:45)
Continuity mistake: When Marion is buying another car at the dealership, in the background you can see the same extras walking in different directions on the sidewalk.
Continuity mistake: When Norman carries Marion's dead body out to the boot of the car, the water on Marion's bonnet changes between shots. In some shots there is water, sometimes there is no water.
Continuity mistake: When Marion steps into the shower and pulls the curtain shut, if you look closely, you can see a rubber bath mat with holes in it. After this shot, the mat is not seen again (during the murder or the clean-up). (00:46:20)
Continuity mistake: While in the shower, Marion rubs her right arm with a bar of soap and her hair has yet to get wet. But in the next shot, the soap has disappeared from her hand and most of her hair is wet. (00:46:45)
Continuity mistake: When Marion gets out of her car at the dealership, she is holding her purse with her hands. But in the next shot, her purse is now around her left arm. (00:17:40)
Continuity mistake: When the Highway Patrol Officer hands the driver license back to Marion, in the interior shot he's holding it out with his right hand and Marion takes it with her left hand, but in the next exterior shot he's handing it to her with his left hand and Marion is taking it with her right hand. (00:15:50)
Continuity mistake: In the scene after Norman kills Marion, when he goes back into cabin 1 to move her body and clean the bathroom, look on the floor between the bathtub and the toilet and you'll see a pair of bathroom slippers. As he mops the bathtub and then dries off the floor with a towel the slippers magically disappear. (00:52:55 - 00:54:05)
Continuity mistake: The shadows made by the sunlight streaming onto the hotel office wall completely change, from the scene in which Sam grills Norman about the $40K, to the shot in which Norman runs out to find Lila. While Sam and Norman were in the hotel parlor and Lila was in the house, who pulled the office window shade half way down - Mother?