Continuity mistake: When General Edel and Martin get in their car at the gas station, the fuel pump nozzle is still in the fuel port of the car. They drive off and the fuel pump nozzle has miraculously removed itself from the car.
Factual error: The model UN uses the new South African flag, but this flag only came into use in 1994.
Family Ties - S1-E22
Visible crew/equipment: After Rygel's transport pod returns to Moya, as the docking bay door slides open, in the shot facing everyone while they have their weapons drawn we can see the bare floor. However, when Aeryn checks Crais for hidden weapons and then as D'Argo approaches him, there's a blue crash mat on the floor. Then it vanishes again.
Visible crew/equipment: When Frasier is standing through his sunroof to speak with the drivers stuck behind him in the parking garage, one shot shows Frasier's body and much of the rear window which features a very clear reflection of the boom mic.
Audio problem: Season 3, Episode 68, "The Duel". Sometimes the tank's co-axial machine gun is firing, but no gunfire sound is heard.
The Treaty - S4-E7
Factual error: At the UN conference, 'England' is shown as a member of the Security Council. England sits on both the UN and the Security Council as part of the 'United Kingdom' - not as a stand-alone country. UN nerds Leslie and Ben would have known this.
Continuity mistake: The scene is shot in a traffic jam on the freeway. The sky has a gray overcast. All close up shots of the irate female driver were filmed in a studio - the background is flat and is a vivid blue. (00:04:00)
Continuity mistake: When Kitty comes downstairs to give the gang cookies, she tells Eric that she picked out an outfit for him to wear on career day. He then turns and mouths the words "Help me." In the next shot you can see Jackie sitting on Kelso's lap when in the previous episode, she broke up with him. In the next shot she is standing behind him. (00:01:00)
Star-Crossed Lovers and Other Strangers - S1-E16
Visible crew/equipment: When Rory asks Lorelai to call Emily to get her out of Friday night dinner so she can celebrate her and Dean's 3-month anniversary, a boom mic drops into the shot as Lorelai stands to get the phone. (00:07:05)
Dirty Harry - S4-E5
Continuity mistake: When Dexter listens to Officer Lundy's tape recording, we hear Lundy say that the Trinity killer's weight is 190 to 200 pounds. When we saw him recording that, he said 200 to 220 pounds.
Other mistake: Right at the start, as they're crashing, the computer narrates their rapidly-dropping altitude in feet. But the "altitude" dial we're shown is in metres. Most noticeable as they cross the 3,000 mark, when the computer voice and the height say/show the same number at the same time, despite the different units. 3,000m would be more like 9,000 feet, or 3,000 feet would be more like 1,000m. (00:03:20)
Christmas Special (2) - S99-E2
Plot hole: Lee and Dawn overstay their tourist visa in the US, then fly back to the UK for the Office Christmas party. They then get into a taxi to go out to the airport in order to return to the US. They're kidding themselves. As I know (to my cost) when you overstay a tourist visa, the US Immigration Service finds out when you check in at the airport on departure. They'll be refused reentry, and probably barred from entering the US for up to six years. (I got a three year ban.) Neither Lee nor Dawn could possibly be unaware of this nor think they could beat the system as they would have been arrested when they checked in in Florida on departure (as I was), and they would have remained in small holding cells until the paperwork banning their return had been processed and their passports stamped 'Invalid for U.S. Entry', as mine was. (All this takes about seventy two hours, so they'd have missed the Christmas party anyway.) The mistake is NOT that they were able to leave the USA - that is explained (it's still not possible, but in the context of the show and the suspension of disbelief we are meant to believe it) the mistake is that they are on the way back to the airport to return. That's absurd. They would have been under no illusions as to their banned status re reentry to the USA.
Continuity mistake: Right at the beginning of the episode a Cadillac Escalade gets stolen. The car is the newest model. The chase begins and the car is a new model right up to a scene when they crash into some other cars. That part was filmed with older model Cadillac. The damage is quite severe, but the chase continues again with the new model that has only one bit of damage - a mirror that has come apart.
The Friendly Physician - S2-E29
Plot hole: The scientist yells for Igor to capture the escaping Castaways, to which Igor responds "capture them yourself" in Ginger's voice. The scientist appears surprised to find out Igor is not Igor, but how can this be? He had to be the one to pull the lever to switch everyone's personalities and bodies around, so he should have already known.
Factual error: The Lockheed 1011 was only produced until 1984. There's no way that in 1999 Toby would be flying on one that "just came off the line 20 months ago."
The Magician - S3-E4
Revealing mistake: When Oliver meets Thea at the Grind and Jot Cafe (Which looks unsurprisingly like CC Jitters) you can see the cups on the table are from CC Jitters. (00:20:50)
Plot hole: When Dominique is on TV, she says she got the shoes from Al's store. Than the Amish guy comes out to confirm she broke her leg from the shoe he made. Al says yes. She got the shoes way before Al knew he had no more shoes and before they even hired the Amish guy. How can she break her leg from his shoe if he wasn't hired and making them yet?
Suggested correction: Al was passing the blame.
Girl Trouble / School Dance - S3-E18
Continuity mistake: Besides the fact that when Helga is sharpening her pencil, the desk arrangement changes, one of the students visible when she looks at Arnold is...Helga.
It's Not What You Link - S2-E19
Continuity mistake: When Phoebe is left alone at the couch, her mom comes up to talk to her. Before her mom shows up, there is a water bottle in front of Phoebe. After Phoebe's mom sits down next to her, the water bottle moves to the other side of the table without anyone touching it.