Other mistake: The opening credits for season 5 show June coming out of the front door with a pitcher of what looks like iced tea, and calling for Ward, Wally and Beaver who are all working outside. But the door opens by itself as she comes out, and then closes by itself behind her. If the entire family is outside, who opened and closed the door?
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.
The Case of the Lucky Loser - S2-E2
Visible crew/equipment: After leaving her husband at train station, Harriet takes a cab to meet a man at a cabin. After a few mins, she takes the man's car to go home. As she drives away, there's a reflection of a man, in suit with glasses (possibly the director) standing offscreen. (00:05:20)
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)
Visible crew/equipment: Diamond parks outside the apartment house, and when he opens the car door, it mirrors several stage lights and reflectors.
The Devil's Necklace: Part 1 - S4-E31
Revealing mistake: Bart teaches Tawney how to wash her face with a bar of soap. When he dries her cheek, the actress' heavy "Indian" make-up is wiped away, revealing a very white complexion. The white patch disappears in the next shot. (00:45:00)
Adios, Señor Magistrado - S1-E26
Character mistake: During the tavern meeting, Sergeant Garcia calls Magistrado Carlos Galindo "Comandante."