Revealing: When Marion is driving her car through the night, she keeps looking at her speedometer. You can clearly see that the gear shift lever is in "park" as she is driving.

Deliberate "mistake": When Norman picks up Marion's body to carry it to his trunk, a bra is visible through the shower curtain. Gus Van Sant included this goof in his 1998 remake.

Factual error: When Janet Leigh is shown lying dead on the floor of the shower, there is a close-up of her open eye. The pupil is contracted to a pinpoint (obviously due to the bright lighting) where it should have been dilated. After the film was released, Hitchcock heard from several ophthalmologists who pointed this out and suggested he use belladonna eyedrops in the eyes of "dead" people in future films, as the chemical prevents the pupils from contracting. (Time)

Continuity: 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.

Visible crew/equipment: While Janet Leigh is being stabbed to death by Mother, as Janet turns around in the shower, it is possible to see part of the moleskin that Janet wore for the scene for a split second. (Time)

Factual error: At the end of the film in the Sheriff's office, you can see a wall calendar with the date on 17. The film started on December 11th - Marion absconds with the money on the same day. She slept the first night in her car, then drove all day Saturday before arriving later that night at Bates motel, she was killed the same night. When Arbogast arrives we learn that Marion has been missing for one week, it is now Saturday, Sam and Lila visit the motel to look for Arbogast, (who by now is dead) and they go to visit Sheriff Chambers later that same evening. They meet the Sheriff the following Sunday morning outside the church, it is on the same day that Norman is captured and taken into custody, now the date on the wall calendar should have shown 20 and not 17, the story has lasted for a total of nine days and not six days.

Continuity: The towel Norman takes off the wall to dry the tub with is white, when he puts it on the back of the toilet it is dark in color and when he throws it into the bucket it is white again.

Visible crew/equipment: When Marion first gets ready to get in the shower, the camera is panning back over the bed to show the newspaper with the cash wrapped up in it.  As the camera pans back, one can clearly see the camera's shadow on the bed as it pans back.

Visible crew/equipment: After Marion's sister and boyfriend look through the Number 1 bathroom and find the ring on the toilet, they turn off the light. On the wall behind them you can make out a square beam of light, but no other lights are on in the cabin.

Visible crew/equipment: When Marion arrives at the car dealership, the salesman sees her and starts walking towards her. If you look carefully, there is a wire trailing out his trouser leg, most likely for a hidden mic.

Revealing: In the scene where Marion's boyfriend and sister visit the Sheriff and his wife at home, there is a camera shot where you can see that living room background scenery ends and there is no ceiling.

Revealing: Mother comes out of her room and slashes Arbogast with a knife. After he falls down the stairs, Mother comes down and stabs him again. But when she does this, her knife has no blood on it.

Continuity: 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. (Time)

Continuity: 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). (Time)

Revealing: After Marion has been murdered there is a close-up of her face. If you look down to her neck you can see her pulse.

Continuity: 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.

Other: In the shower scene, Marion Crane's palm looks water wrinkled as if she's been in the shower for quite a long time even though she was only in for a few moments before Norman stabs her. Also, when Norman drags her out of the bathroom, Marion's legs are stiff and together and she has her toes pointed.

Continuity: Norman brings a tray of food to Marion, when she says "So long as you've fixed supper we may as well eat it," watch how her folded arms change position from hands tucked underneath, to hands on top of her arms.

Continuity: 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: 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.