Audio/visual unsynchronized: When John Blane tests the safety of the gun on his friend, you can see the hammer fall about one second before the accompanying sound effect is heard.
Continuity: In the final scene in the mediaeval throne room, the position of the queen and the knight on their seats changes from shot to shot, and the knight's hand moves from palm up to palm down.
Continuity: In the last scene of the film, the gunslinger rises from the floor for the final time, and turns to reveal that its face-plate has fallen off. But the faceplate, clearly visible on the floor when the robot turns, wasn't there seconds before when the robot pushed itself up.
Continuity: Robot Gunslinger's clothes after being splashed with acid.
Continuity: During the fight between the Medieval Knight and the Black Knight, the bent sword switches between characters several times.
Revealing mistakes: In the throne room where Peter has the confrontation with the gunslinger, the Medieval Knight can be seen breathing, although he is supposed to be an android with a dead battery.
Continuity: When Peter kicks in the bedroom door, he fires more rounds that the revolver's capacity.