Continuity: When Charley Butts first gets to Alcatraz he is inside his cell and introduces himself to Frank Morris. According to the camera angle, Charley's cell is on the right and Frank's cell is on the left. Later on, it's like they switched cells. Frank's cell is to the right and Charley's cell is to the left. But later their cells are back in their original positions. Video only.

Visible crew/equipment: In the non-widescreen version, a hole in the ceiling and a microphone can be seen picking up the dialogue between Patrick McGoohan and Clint Eastwood in the warden's office.

Continuity: In the scene where Charlie Butts arrives at Alcatraz, he has to take all his clothes off for a routine check. When the guards escort him to his cell you can see him wearing a pair of white boxers, but in the next scene (still walking) he is naked again and when placed into his cell you can see him wearing a pair of pants.

Continuity: In the dining hall when the guard calls Frank over to talk about the "accident" involving Doc, the food on Frank's tray is different when he walked over from when he walks away.

Continuity: When Wolf goes for Frank in the yard with a knife, his blue woolly hat disapppears for one shot when he is swinging the knife at Frank. It's snuggly back on his head in the next shot.

Continuity: When Doc is painting himself in the yard, the amount / position of grey marks on the painting differs.

Factual error: The movie is supposed to take place in 1960, but the oscilloscope on the metal detector outside the wood shop is a new 1979 model, the year the movie was made.

Factual error: In the opening scene that shows San Francisco scenery there is a shot of a large TV tower called Sutro Tower. The film takes place in 1960 and Sutro Tower wasn't built until 1973.

Continuity: When Frank is throwing black checkers into the corner of his room, between shots after he spots the bug, the amount of black checkers sitting on his board blatantly decreases.

Revealing: Frank is put in Block-D. Then one guard comes and slides open the door, and light pours onto Frank (who is curled up in the corner). It goes to a shot of the guard standing behind the bars, which he has not yet slid open. But in the previous shot when the light was on Frank, there was no shadows cast from the bars - there should have been...