Continuity mistake: "Night of the Bubbling Death": The dust left on West's jacket after the fight changes patterns several times, then disappears altogether when he enters the building. A shot of his feet shows us that his formerly dusty boots also polished themselves. (00:04:00)
Continuity mistake: "Night of the Arrow": President Grant's cigar keeps getting longer, shorter, and longer again as he gives West and Gordon their special assignment aboard the train. (00:08:10)
Continuity mistake: "Night of the Bubbling Death": When Grigsby first approaches the stolen U.S. Constitution, it's under glass (we can see the light reflections). But seconds later he lifts the paper without removing the glass, which has disappeared. It's back later, when West must cut it to retrieve the document. (00:09:10 - 00:36:30)
Continuity mistake: "Night of the Arrow": When Artemus pours the president a drink, the glass is only 1/4 full. When Grant picks it up, however, it's suddenly 3/4 full. (00:09:15)
Continuity mistake: "Night of the Bubbling Death": Artemus tosses just one bottle grenade at the pursuing posse of bad guys. In the next shot, however, multiple explosions go off all at the same time in a straight line across the road. (00:14:00)
Other mistake: "Night of the Bubbling Death": When West lifts the unconscious bad guy by the shoulders and prepares to drag him out of sight, you can see drag marks already in the dirt from previous takes. (00:21:10)
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)
Continuity mistake: "Night of the Bubbling Death": West uses a glass cutter to retrieve the US Constitution, which was lying flat under a covering sheet of glass. But when he reaches in and pulls the document free, it is no longer flat, but is rolled up. (00:36:15)
Continuity mistake: "Night of the Arrow": West and Gordon leave two champagne bottles and four glasses sitting on the table when they walk away to answer the door. When they return, the bottles and glasses have all completely changed positions by themselves. (00:41:30)
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)
Factual error: "Night of the Lord of Limbo": At the end, Vautrain tells West and Gordon to go through the door on their right. The door is on the camera's right, but is on West's and Gordon's left. (00:45:10)
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)