Continuity mistake: In the final scene at the sheriff's office, Mitchum has his feet up on the table top, and the boot soles are clean. But after Wayne walks out, there is suddenly a spot on a boot sole. (This is visible in the video)
Continuity mistake: When Blondie abandons Tuco in the desert, watch the rope around Tuco's neck. It changes between shots, sometimes over his left shoulder, and sometimes hanging down in front of him. It is not due to the camera angle.
Continuity mistake: When Belle Armitage first shoots her pistol at Johnny Finger, she drops it down the front of her dress. Seconds later, it reappears up between her ample bosom.
Continuity mistake: When rescuing Burt Lancaster whilst tied upside down in the canyon, watch the two bandits behind Lee Marvin when he jumps down, as they retrieve the rifles stood up against the rocks twice.