Goofs

When Reagan and Joe Downing are on the prison wall, their medium shot is undercut with a long shot, obviously archival footage from an earlier film. The mismatch has Reagan's Bancroft go from wearing a hat with no gun to no hat and holding a pistol while Downing's character Dice goes from no hat and a pistol to a hat and a rifle.

One cannot effectively attach a silencer on a revolver and expect the silencer to work. So it could not be used to kill Parker.

It is physically impossible for the machine gun tower to fire bullets at the escaping prisoners on top of the wall and then still fire at them once they have jumped over to the other side of the wall - thus firing on both sides of the wall.