Goofs

When 'Freshman' Stack (Jeff Corey) is washing his hair, it alternates between lathered and not lathered.

When Munsey starts fighting Collins, he pulls out the ammunition belt from the machine gun and starts hitting Collins with it. But on the following cut, the ammunition belt is now back in the machine gun. Then on the following cut after that, the machine gun is again without the belt.

When Munsey talks to Gallagher in the dining hall, the position of the hands of Jackson (the guard standing behind) changes between shots. In the longer shot, he is holding the baton with his hands on top of the baton; in the closer shot, his right hand is still on top, and his left hand holds the baton from underneath.

When Joe Collins is inside the towers and kills the second guard just above him on the spiral staircase, it can be seen by the shadow that the guard's body slumps on the curved handrail just a couple steps up. But as the wounded Collins starts climbing up the stairs, the body of the second guard is nowhere to be seen.

When discussing the hill attack during the war, the positions of the convicts change between the shots from outside the cell to the ones inside.

Soldier is in prison after taking the blame for a murder that took place when he was serving in Italy with the U.S. Army. Therefore, he would not have been in a civilian state prison. He would have been sent to the U.S. Disciplinary Barracks at Fort Leavenworth, as he would have been court-martialed while still being a member of the U.S. Army. At the least, he would have been sent to a federal prison if he'd somehow (highly unlikely) been able to get sent to a civilian facility.

When Munsey enters dining hall for first time, he is wearing a hat with an airline insignia.

When Collins is fighting Munsey, he knocks out Munsey unconscious by head butting him in the stomach. However, a headbutt to the stomach may make a person double over in pain but will not knock a person out cold.

During the fight in the guard tower between Munsey and Collins, guard Tom seems to have been killed, but the stunt actor Tom Steele who plays him is clearly doubling Hume Cronyn.

Under the opening credits (and in other shots), the rain is coming down in two distinct directions.

When Collins and Gallagher walk over to talk to Crenshaw in the print shop, a shadow of the boom microphone is visible on the column top left of the frame, and it is visible on the same column again as they walk away.