Continuity mistake: When Norton loads his gun the bullets are scattered over the table. When he takes aim the bullets are neatly in one place, but after has has shot himself they are scattered as before. (01:56:45)
Continuity mistake: In the scene where the warden is tossing cells and comes to "size up" Andy, it shows all of the chess pieces on the window being knocked over while one is in the guard's hands. After a short time one of the pieces is upright again, without anyone touching them. (00:48:30)
Continuity mistake: Andy is discovered missing. While the warden is walking to Andy's cell, he tells the guard to question "him", meaning the Morgan Freeman character. He points to Freeman with his left hand but when the scene changes its point of view he is pointing with his right hand. (01:45:45)
Continuity mistake: As Norton kills himself, the glass that blows out behind him is quite large and about half of the frame gets blown out. There are a few specs of blood on the window as well. A couple of shots later as the camera pulls back and shows Norton you can see the hole in the window is quite small and shaped differently and a smear of blood above the hole now. (02:03:40)
Continuity mistake: When Andy is in the bank, in the background you can see a man in a "porkpie" hat and a white shirt move forward to talk to the cashier. As Andy stands up to leave, the man can be seen again, standing towards the back of the queue. (01:56:10)
Suggested correction: The man may have made an error to some paperwork (deposit slip or withdraw slip), and had to get another one and fix his mistake...which would have put him at the end of the queue. You don't get to jump back in line, unless offered that convenience.
Continuity mistake: When Red finds the metal box he takes out an envelope in a plastic bag, folded up on the right side. When he opens it the crease is on the left side. He hasn't turned it over. (02:07:30)
Continuity mistake: When Norton prepares for his suicide you see on the desk a photograph and, a bit away, a lamp. After he has shot himself the photograph is leaning against the lamp (it was too far away in the previous shot to have fallen against it). There's also some sort of card open on his desk on some paperwork which suddenly moves onto bare desk and gets shorter. (01:57:10)
Visible crew/equipment: When Sgt. Hadley nearly throws Andy off the plate factory roof, the reflection of a boom mike is briefly visible in the shiny brim of Hadley's hat. Andy dropped the tar mop before approaching Hadley, and there are no other objects in this shot that could have caused the reflection. (00:35:00)
Continuity mistake: When one of the "sisters" gets beaten up by Capt. Hadley he tries to escape from his cell and holds on to the bars on the other side of the passage. From the side his right hand grabs a diagonal bar, but seen through the bars he is holding on to a vertical bar. (00:43:15)