Continuity mistake: When Christine is fixing herself after the guys smashed her up, her front end is shown to be perfectly straight for its entire width and the hood is missing. Near the end of the scene, the front end is shown crushed and unfolds again, and the hood appears from nowhere.
Continuity mistake: Eddie drives a 1957 Chevy convertible off the bridge. A scene showing the car being fished out of the water clearly has an older vehicle dangling from the line.
Suggested correction: The car pulled onto the bridge is absolutely a 1957 Chevrolet convertible.
Visible crew/equipment: When Dr. Raymond leaves with Mary in his car after talking to Norman, when he drives off the entire crew and equipment can be seen reflected in the side of his car. (00:41:50)
Revealing mistake: The outline of the blood pack is visible under John's shirt when Stillson's body guard shoots him. (01:37:35)
Continuity mistake: When Meg comes up to Angela, taunting her, Angela's head position and the look on her face changes in each shot.
Plot hole: It seems unlikely any mental institution would let a patient out to visit home for any length of time as happens in the movie with the killer and his mother.
Suggested correction: Unlikely, but still possible. Almost every workplace has a situation in which a person is bending the rules.
Visible crew/equipment: Naomi Arai snuck back home from the window. When she walks down the stairs to go in the dining room, you can see on the upper floor wall to her left the shadow of the camera crew following her. (00:01:20)