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)
Visible crew/equipment: When Mulder and Scully enter the abandoned mine through a doorway, the viewer can see at right in the distance a number of people sitting on a wall, and one crouching in front of the wall with what looks like a dog. They are sitting still, but there is still movement there. (00:16:00)
Revealing mistake: There are numerous times throughout the series where the supposed big city of Metropolis is actually just a back lot set and none of the buildings are more than a couple of storeys high. Quite often the green hills of Southern California can be seen beyond the set and between the buildings.
Continuity mistake: The age gap between Eric and Cory decreases as the series progresses. At the start of the show, Cory is in 6th grade and Eric is a high school sophomore, meaning they are four years apart, give or take a few months. By season 3, Cory is in 9th grade (confirmed by dialogue mentioning that Shawn, who is in the same grade as Cory, is 15 years old), and Eric is a senior, leading to an age gap of three years. The first episode of season 4 takes place a couple months after the end of season 3, with Eric and Cory returning from a summer Road Trip, but just two episodes later, Cory mentions that he is in 11th grade, while Eric is still barely out of high school, leading to an age gap of two years.
Other mistake: Jack follows J. Edison Nash to a wine warehouse and watches as Nash punches numbers on a keypad in order to gain entrance to a private room. Nash punches the 6 and a beep is heard. He then punches the 8 and another beep is heard. During a close-up of Jack, four more beeps are heard, for a total of six. Jack says the number out loud - 862, which is only three digits.
Continuity mistake: In an interior shot of the detectives' vehicle, the car is a late 80s Chrysler (LeBaron or K-Car), obvious from the 'pentastar' logo on the steering wheel and the distinctive gauge layout. When the detectives walk away from the car, it is the homicide standard issue Chevrolet Cavalier.
Character mistake: Trivette hands the man in yellow a bullet recovered from the plane Walker and Alex were traveling on, which was shot down by an assassin flying a P-51 Mustang. This man, and later Trivette, mistakenly refer to the round as a "50mm," when in reality, Mustangs were equipped with M2 Browning .50 Caliber (12.7 mm) machine guns. (00:30:25)
Show & Tell - S6-E10
Continuity mistake: During a conversation with Diane, Jill says that her son is with his dad. In the conversation she calls the dad "Ken." In future episodes Jill's husband is called "Don." (00:03:55)
Dr. Quinn, Medicine Woman - S1-E1
Revealing mistake: While Dr. Mike is riding in the wagon with Charlotte and her children, when Charlotte says, "I'd like to ring Sully's neck," a vehicle is visible behind Charlotte's head driving toward the left side of the screen. (00:20:05)
Continuity mistake: In an earlier season Caine takes a young Peter to a place in the temple and explains that his mother is buried there. However in the series finale he shows adult Peter a picture that someone took months ago and Caine tells Peter that the woman is his mother and he's going to find her.
Ryuusui, Chimaera no Otoko - S1-E1
Continuity mistake: When Crosswords has the first attack of Chimera witnessed by Black Jack, his wife Sayuri runs to the fridge to grab the bottles. In the shot with the camera inside the fridge, there is a full complement of bottles in the bottom shelf, but in the other angle the right half of the shelf is occupied by glasses only. (00:09:15)