Broken Link - S4-E26
Revealing mistake: During the fight between Garak and Worf near the end of the episode, a Jefferies tube door is knocked out of its frame to reveal the end of the set - a dark room with a wooden scaffold and various other pieces of equipment (slow-mo helpful but not required). (00:36:00)
Revealing mistake: Any time any character is driving a Suburban, or any other vehicle with a column mounted shift lever, the shifter is in park while they appear to be driving.
The Night of the Bubbling Death - S3-E1
Revealing mistake: As West drags the body of a bad guy out of the scene, the supposedly unconscious man is holding his head up so as not to have his head dragged through the dirt. A truly unconscious person's head would flop back on to the ground.
Revealing mistake: When C-Note leaps out of the train, you can see that the man jumping out of the train is a stuntman. He is much chubbier than C-Note (wearing a life vest) and his face is completely different. (00:22:20)
Revealing mistake: The captain's arm that was removed can be seen wrapped in a green screen editing sleeve when he is in the hospital. (00:39:55)
Revealing mistake: Throughout season 2 on several occasions it's clear that John Terry (Bob Warner) is wearing a fake mustache and a fake beard.
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)
The Werewolf - S1-E5
Revealing mistake: It is obviously a dummy in a woman's dress The Werewolf throws into the empty swimming pool.
Episode Five - S1-E5
Revealing mistake: The mirror over Barnabas' mantel hangs flush against the wall. Yet when he shatters it, the candlestick he throws can be seen to go through the glass instead of bouncing back as it should have done. (00:43:45)
Revealing mistake: Season 5 Episode 18 "Spark of Life": when they show a closeup of the badly-burned woman during her debridement, it can be seen that even though her eyebrows and hair and, in fact, 90% of her skin has been burned away, she still has long, full eyelashes.
The Prodigal Son (1 & 2) - S2-E1
Revealing mistake: After Crockett and Tubbs' confrontation with the New York police at the end of part 1, as the police car drives away, in the background a blue car drives by and a man and woman can be seen in the car looking and pointing at the filming.
Revealing mistake: The solid brick wall bends like vinyl when Colonel Malloy touches it.
Revealing mistake: When Victor is opening the padlock, sparks fly around in close ups. In the wide angle shots there are no sparks at all.
Food Fight - S1-E6
Revealing mistake: When Pudgy Pig is standing outside of the food packaging plant, a human hand can be seen sticking out of Pudgy Pig's wrist. (00:15:30)
Tabula Rasa - S1-E3
Revealing mistake: With Marshal Mars in pursuit, as Ray drives his pickup, he holds the steering wheel with his left hand, and his stiff prosthetic right arm is down at his side. When Kate grabs for the steering wheel, in the side exterior shot the stunt driver is quite noticeable, as he grips and turns the steering wheel with his good right hand/arm. (00:30:40)
Revealing mistake: While Horatio and Alexx are examining the prostitute's body, you can see the corpse breath in a side view.
Revealing mistake: Davis, the psychiatrist, is the second man to be killed. Although he was shot at five times, only the first two wounds, which are the highest, give blood, while the lower and later three do not.
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)
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".