Continuity mistake: In the scene where Eastwood is watching "the city of Lago volunteers" training,he is drinking a beer. The first time he lifts the glass to drink, it is about half empty. After he says something to the man with the knife, he lifts the glass for another drink and it is nearly full.
Continuity mistake: When Chino ambushes Morrel's men in the mountains he is waiting on a pointy rock. When the camera angle changes there are bushes behind him that weren't there before. (01:27:05)
Continuity mistake: At the start of the movie the train pulls into town. The loco, tender and 2 stock wagons pass the water tower, but the next shot shows the loco still alongside the water tower.
Continuity mistake: During the first gunfight between The Gunslinger (Yul Brynner) and Peter (Richard Benjamin), The Gunslinger is seen being shot in the middle of the body from the back. But, when you see him a second or two later, the shot is well over on his right side.