Other mistake: When Snoopy starts sneaking through the pumpkin patch, Sally is standing with her arms crossed and Sally's hand is painted blue while talking to Linus. (00:20:35)
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 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: 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.
Continuity mistake: Alva 'mistakenly' enters Owen's room. In the side views showing both characters, Robert Redford's hand is on his belly, while shot from the other side his hand rests on the mattress. (00:25:10)
Visible crew/equipment: During the flashback scene in the clock courtyard, there are multiple T-marks (plastic type) visible on the ground, near Col. Marcus and Gen. Randolph. (00:16:20)