Continuity mistake: When Shepherd Book tells everyone about the electrical nets, Jayne says, "One day you're gonna tell us all how a preacher knows so damn much about crime." Shepherd then turns to leave. But in the immediate close up of him and Mal, he turns to leave again.
Visible crew/equipment: After Charles confronts Choi Sung Ho about the candy, Ho explains that he sold it on the black market to buy real food, and when Ho reenters the mess tent through the side door, we can see that outside there's a director's chair, which actors also use, with something printed on its back.
Revealing mistake: Carl, Eddie, and Steve are out ice fishing. At one point Carl falls through the "ice" and you can clearly see that the "ice" is made of some sort of styrofoam. It looks like the stuff used for packaging. The snow looks just as fake.
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)
Continuity mistake: Prior to bringing Ray up for the role-playing exercise, the parenting teacher erases a circled phrase from the chalkboard. Throughout the scene, the chalked circle flips several several times between being totally erased and having a faint outline left over.
The Night Dr. Loveless Died - S3-E4
Continuity mistake: In the opening scene, a cowboy sitting atop the balcony above Big Brad's Bar gets up and approaches the balcony's edge twice.
Continuity mistake: When Sherlock is backstage at the circus and finds the yellow spray paint, he draws a line on the mirror. In the next shot, the line he drew is completely different (and in fact is more of a squiggle). (01:07:40)
Visible crew/equipment: When Chester and Cassie are in The Cabin, Chester is looking through the picnic basket while Callie holds on the Indian's hand and talks to him. In the scene behind Callie is an unidentified man who disappears when the scene cuts to Chester. (00:47:00)
Enemy Fire - S3-E2
Continuity mistake: In episode 2-4 "The Funk Hole " which takes place in the fall of 1940, Andrew states to Sam that his mother died when he was eight years old. In this episode (Feb to June 1941), Foyle is looking at his wife's grave; it shows his mother died in 1932, which would have meant Andrew was born in 1924, and only 16 in 1940, far too young to be a Spitfire pilot. Also, his commanding officer states "the younger pilots look up to you, Andrew", before one of the "younger" pilots (age 19) is badly burned in a crash in Andrew's plane.
She Loves Me, She Loves Me Not - S8-E2
Visible crew/equipment: After Jack talks to Larry about the magazine quiz Jack asks Janet if anything's been bothering her, and just as Terri walks out of the kitchen holding the two cans, a crew member's hand can be seen behind Terri placing a bag on the counter. (00:04:15)
Character mistake: Throughout season 3, whenever someone visits Henry in prison, the word "VISITOR" on their visitor tags is misspelled as "VISTOR."
Character mistake: When Gina tries to set up Rosa on a date, Rosa mentions the last person Gina set her up with (Justin) was a dork who rode a Yamaha motorcycle. She says "he might as well have picked me up in a station wagon." Rosa's bike is a Yamaha R1.
Transylvanian Homesick Blues - S2-E65
Character mistake: Ray says that it's the very first time they've dealt with vampires. In Season 2 Episode 25, "No One Comes to Lupusville", the Ghostbusters had to deal with both werewolves and vampires.
Factual error: Sgt. Carter is wearing a plain belt buckle with his dress blues uniform. Since Sgt. Carter is Gunnery Sgt, he is a staff NCO so his buckle should have the USMC emblem on the buckle. (00:24:00)
Visible crew/equipment: When Dewey yells for Lois because the bow was put on the present, if you look to the left of Lois, you will see a crewmember kneeling down, handing Lois the Red Dress, who is holding a bucket of water. He quickly gets out of the camera's view. [This is on the DVD of the first season. Someone said on the audio commentary that after catching it, they deliberately left it in to see if anyone would spot it. It's still a mistake, but that's why it's there.]
Audio problem: At the end of the show when Alice is blowing the whistle, the whole family comes to the top of the stairs. Mike says "Alice, it's 6 o'clock in the morning" Watch his mouth. It looks as though he curses and the (curse) word was dubbed out.
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)
Plot hole: In this episode, the Duboises make such a big deal about Ariel being old enough to finally learn to drive. However, two episodes previously ("Things to Do in Phoenix When You're Dead") Ariel drove to school with Joe, and Joe complimented her on her prowess.
Continuity mistake: During the episode when Claire and Phil do their warm-up before racing each other, their children Alex and Luke arrive from school. They get down from the car, and the car takes off and goes away. But in the 2nd shot we can see that same car parked in front of them. (00:17:00)
Free for All - S1-E4
Continuity mistake: Throughout the episode, Number 6's lapels switch from having solid to broken white piping and back again.