Visible crew/equipment: As the Batcoper emerges from its hangar, multiple crew and equipment are reflected in the cockpit's glass bubble. (00:04:05)
Continuity mistake: When Lucy awakens at 4:00 AM she checks on Linus and then puts him to bed. In some shots there's a window over Linus' bed, but in other shots the window has vanished, and there's only a shelf over the bed. (00:23:10)
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.
Revealing mistake: When the stagecoach driver gets hit with an arrow, it springs up from below into a horizontal position. (00:33:55)
Continuity mistake: Alva just learned about Legate's true profession and is standing now in his room shouting at him. In the closer shot, her necklace is running on the rightmost part of her right breast, while it is more centered in the wider shots. (00:55:10)
Continuity mistake: When Don Knotts is in the old Simmons mansion, he falls down a chute of some kind. If you watch closely you will see the stunt person looks nothing like Don Knotts. It is a younger man with very straight hair.