Continuity mistake: Where Swazye and Moore are at the pottery wheel, seconds after their hands and arms had been smeared with clay, they're clean.
Suggested correction: The director explained this in the commentary. The scene where they are clean isn't meant to be immediately after the clay pot scene. It was just the same evening.
Continuity mistake: When they are in the library after they found out Stan committed suicide, it shows Beverly stand up but when it cuts back to her she is sitting down and stands up.
Continuity mistake: At the jail bus arrival, the new African American inmate (with orange suit, as the other new ones) is getting off the bus handcuffed and wearing sleek black glasses, next shot, the glasses are gone (handcuffs still on). (00:10:18)
Continuity mistake: When Jacob is talking on the phone while shaving, the amount of shaving cream on his face changes from shot to shot.
Continuity mistake: Norman pours poison into the pitcher of iced tea. In the next shot, we see him carrying the pitcher and two full glasses on a tray - but the level of liquid in the pitcher hasn't changed, even though he's supposedly filled the glasses from it. Later, when the pitcher is sitting on Mother's dresser, the pitcher's level is lower, but no one has poured anything from it. (01:00:05)