Revealing mistake: When Elsa is waiting in the lobby, she's wearing a dress which shows her normal, not wooden legs. It's very apparent when she is crying on the floor.
And Then There Were None - S6-E16
Revealing mistake: Samuel is very much dead, laid out on the table in the canning factory employee lounge, but as Sam stands over him, talking about whether or not it was right to gank him, you can see Samuel's chest rising and falling as he breathes. (00:26:30)
Revealing mistake: When Sookie finds Dawn dead, in the close-up of Dawn's body, you can see the actress' pulse at the base of her neck. (00:50:55)
Revealing mistake: When Rick checks his revolver before holstering it, there are no primers in his cartridges.
Revealing mistake: 1967: Barnabas and Vicky are talking in Collinwood's foyer when a great deal of noise starts interrupting the scene from backstage. You can hear coughing, several bumps and crashes, shouts, and finally, a fire extinguisher going off. Meanwhile, the distracted actors are completely blowing all their lines - but the unstoppable taping goes on.
The Werewolf - S1-E5
Revealing mistake: It is obviously a dummy in a woman's dress The Werewolf throws into the empty swimming pool.
Revealing mistake: The solid brick wall bends like vinyl when Colonel Malloy touches it.
Revealing mistake: While the computer is being infected with the virus, Peterson turns away from the screen to face Scully. Two seconds later, after the shot of Scully, the same shot is shown again but in reverse so that Peterson turns back to the screen. It's more obvious if you look at the weird way his eyes blink in the reversed shot. (00:39:50 - 00:41:32)
Revealing mistake: The re-use of a brief scene from the pilot episode, inserted during Nick and LaCroix's vampire battle in the warehouse, creates the unfortunate problem of Nick completely changing clothes in the middle of the fight. (00:37:35)
Night of Desirable Objects - S2-E2
Revealing mistake: When the typewriter is being used at the end, the keys being pressed don't correspond to the words appearing on the paper. Obvious from the start - the first letter pressed is on the middle row of the keyboard, but the first word typed is "unacceptable".
Revealing mistake: When Leland Palmer is locked in the cell he starts screaming and runs headlong into one wall, then the other. The first wall wobbles noticeably on impact, indicating it is being shot on a set.
Revealing mistake: We see Redfield's car strike the invisible barrier from a side angle. It jerks to a stop and the hood flies up, but there's no other front end damage - until the angle shifts to a forward view, a shot of an identical car that had been previously wrecked. Now there's suddenly considerable damage to the front end, and the hood is in a different, much more crumpled position. (00:11:10)
Revealing mistake: In the scene where Norman visits Caleb at the motel on his own, after hearing Norma and Dylan argue, he gets into an argument with Caleb. Norman then pulls a knife out high above his head, at which point you see it is a prop/rubber type knife. The handle aimed at Caleb but the force Freddie Highmore has used to pull the knife up and back causes the blade to bend and aim toward the ceiling.
How The Elephant Got Its Trunk - S3-E6
Revealing mistake: The white around Papa's lips and eyes is slightly running when he is sprayed with water. however the white is supposed to be part of his real skin.
Revealing mistake: Julia is throwing the tennis ball at the wall and is turning around to talk to Barbie. The military truck on her right has its front drivers tire on the line where the wall is supposed to be. This would mean that the whole front of the truck would be inside the dome. (00:07:44)
Revealing mistake: The eyes of the actor playing Gideon the robot can be seen through the eye slits of the robot mask in some shots.
Revealing mistake: In the bakery, Will plays a lively tune on the concertina - without touching any of the button-keys necessary to play the notes. (00:26:15)
Night of the Living Dummy III (2) - S2-E25
Revealing mistake: When all the dummies are set up in Zane's room, you can see in many shots that what is meant to be Zane as a dummy is a complete human.
Revealing mistake: The corpse's chest rises and falls before Milton resurrects it.
Stalk Like An Egyptian - S1-E10
Revealing mistake: At the beginning when the Egyptian mummy puts the ring on his finger, the tip of the finger bends like a glove.