Revealing mistake: "Night of the Jack of Diamonds": During his fight with West, Sordo the bandito, who has a gray beard, is suddenly several years younger with a dark brown beard, thanks to the substitution of a stunt double. (00:35:30)
Revealing mistake: "Night of the Bubbling Death": Artemus takes off his coat and is wearing smoke canisters strapped to his back underneath. But the close fit of his jacket in previous shots reveals that the device wasn't there until just before he began removing the coat. (00:43:15)
Revealing mistake: "Night of the Running Death": During West and Gordon's poker game at the end, Gordon tilts the table by at least 30 degrees - and none of the poker chips, cards or cash moves an inch. Apparently, everything was glued down. (00:44:30)
Revealing mistake: "Night of the Underground Terror": During the climactic fight scene, James West's famously tight trousers rip apart in the crotch, amply revealing his very 20th-century white jockey briefs. A few shots later, that rip mends itself and the pants are split (much more decorously) down the right outer seam instead. (00:46:00)