Revealing mistake: West and Gordon burn a perfect circle (unlikely in and of itself) in the metal floor in order to break into the dungeon below. West punches the circle out with his fist, then grasps what should be white-hot edges with his bare hands before jumping through the opening. Even if wood it would still be too hot to touch. (00:32:00)
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: West tosses a small grenade at the French doors. We see it hit and explode without breaking a single pane or crosspiece. It just makes smoke and blackens the surface. After a shot of West and Gordon, we cut back to the door and it's now a broken ruin with no glass and the wood framing destroyed. Delayed action bomb? (00:13:00)
Revealing mistake: At the beginning of the episode, as Jim West walks away from the newsstand vendor and closes the magazine, a 1967 ad for DieHard batteries ("The DieHard Fights the Common Cold") can be seen on the right-hand page of the prop magazine, in a modern sans serif font.
Revealing mistake: About half way through this episode, the hooded man West is chasing goes through double doors and closes them. West slams his body to open the doors. He steps back to ram his body into the doors again to force them open. Before he does, we see the doors sort of slightly move back and forth (this looks very odd and unnatural) before West slams them open.