The Rex Montana Story - S1-E35
Revealing mistake: When Flint follows the Indians, there's a strong wind blowing. But the two puffy clouds in the backdrop sky never move.
Three Bells to Perdido - S1-E1
Visible crew/equipment: When Paladin talks to the ranchers, two equipment shadows are moving on the wall at the upper left of the screen. (00:03:00)
Adios, Señor Magistrado - S1-E26
Character mistake: During the tavern meeting, Sergeant Garcia calls Magistrado Carlos Galindo "Comandante."
The Town That Wasn't There - S4-E3
Continuity mistake: John Astin, playing a homely sheep farmer, wears a large fake nose throughout the episode. But in the saloon meeting scene, where Beau introduces him to the townsfolk, the nose is conspicuously missing.