Corrected entry: When Norman is cleaning the bathroom, he leaves the toilet seat down. But later, when Sam and Lila go into that same bathroom, they find the seat up. (00:53:50 - 01:32:50)
Corrected entry: When Norman carries his dead mother down the stairs her legs are not stiff at all, but wiggle around loosely as he turns at the banister and begins his stairway descent. However, it may have given the plot away if she looked dead and stuffed at that point in the movie, but if she had been dead for many years (I assume stuffed by Norman), they would be stiff and rigid and not bend loosely below the knees.
Corrected entry: After Marion has worked out how much money she owes back when she decides to return to Phoenix, she rips up the piece of paper she wrote it on and throws it into the toilet. Later on her boyfriend and her sister come to find where she is and enter the bathroom she was killed, the sister looks down next to the toilet and there is a piece of the torn paper which she picks up. However when Marion was tearing up the piece of paper you can see that all the bits fell directly into the toilet making it impossible for that piece to be there.
Corrected entry: In the Scene where Norman spies on Marion, he is looking right into the bathroom, but his office is next to her bedroom, rather than the bathroom. Hitchcock did this on purpose though, to see if anyone was paying close attention.
Corrected entry: When Norman goes to clean Marion's room, he goes into his office and comes out with a mop. Yet when he enters Marion's room, Norman also has a mop bucket with him (which he did not have before). (00:50:55)
Corrected entry: In the shower scene after Marion has been stabbed, she slowly slides down with her back against the shower wall - you can see the blood from her back streaking down the wall and into the tub, but when Norman comes in to clean up, the wall is clean, and the only blood you see is in the tub and on the floor.
Corrected entry: 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.