It May Look Like a Walnut! - S2-E20
Character mistake: Rob is having a nightmare, part of which involves the disappearance of his thumbs. When he finds Laura at home, the script calls for him to say, "I want you to help me get my thumbs back," but he actually says, "I want you to help me get my thumb backs." His thumbs are also still there but hidden (you can see a portion of them in one frame of the episode).
House Party - S2-E5
Continuity mistake: Kelly said her youngest brother can burp his whole name Kenneth Leonard Kapowski in one burp. However in the previous year, Kelly had an infant brother named Billy. According to this info, unlikely Kenneth would be younger than Billy.
Suggested correction: Kelly can have more than one brother because in the episode where Kelly gets her job at the Max she said "I cook every night for my 11 siblings". So he could be younger or just have a nickname.
The mistake is valid because she says her "youngest" brother, not "younger." In the episode "The Babysitters" (which was meant to air in season 1 and produced before "House Party"), her brother Billy is an infant and says his first words. Kelly has 6 siblings and she never said she cooked for 11 siblings when getting a job at The Max. She says she sets the dinner table for 9 people three times a night.
Ironically, the show only reveals 5 siblings each in their own individual episode. (#6 is unknown). Bennett (mentioned), Nicki (seen), Kyle (voice heard only), Kenneth (mentioned), Billy (seen) are the 5 of 6 siblings revealed.
Continuity mistake: Ruth is seen in a flashback. The young Ruth has a mole on the left side of her face, as does the adult Ruth. But in one shot, when she is slapped by her father, the mole appears on the right side. (00:20:00)
Continuity mistake: When Buffy is talking to Riley, she puts the scarf on her head, on his hand. He talks to her and says "Maybe I am the bad guy," and in the next frame her scarf is back on her head again, then off again in the next frame. (00:24:20)
Other mistake: When Lucy is in the cafe watching the mother and her children, the mother repeats the same dialogue.
Factual error: A character in the episode has invented denim, but denim was invented in 1873 and was being used widely up to the time period of the series, which is set in 1893.
Suggested correction: The entire series was set in an alternate history of sorts, so most, if not all, historical "inaccuracies" cannot be regarded as mistakes.
The Suitcase - S4-E7
Factual error: At the beginning of the episode, the male employees are all discussing James Bond. It is mentioned that 'James Bond goes underwater, he met a girl underwater'. This refers to the plot of the movie 'Thunderball' (it does not occur in the Thunderball novel, nor any novel or film prior to this). The main plot of this episode centres around the Sonny Liston VS Cassius Clay fight in May 1965, and 'Thunderball' was not released until December of that year.
Todos Los Hombres del Presidente - S3-E9
Visible crew/equipment: During the car crash, one of the camera shots is from above and you can see a camera vehicle moving into the shot from the bottom with the camera mounted in front of the vehicle. (00:35:25)
Visible crew/equipment: In the first scene of the episode, a crew member is visible through an open door beside the staircase.
Factual error: In the mall where Jimmy meets Irene there is the Pandora logo in the background when Jimmy is going up the escalator. Pandora didn't open its first store in New Mexico until 2013. (00:27:00 - 00:28:00)
Continuity mistake: On the video of Ian supposedly killing Alison, we see her arm fall to the ground with her "Alison" bracelet visible. But in a later scene where Emily watches Ian put his bag in the athletics room, we cut back to the video and Alison's arm suddenly has a sleeve covering up her bracelet. When we see the video again later in the series, her bracelet is visible again.
Continuity mistake: This is a mistake for the introduction from seasons 2-20 (1991-2009). When Homer screams, he turns round. You see this in a wide shot. There are no boxes to the right of the door in the garage. However, two just appear out of thin air when he runs through the garage. (00:01:50)
Other mistake: The opening credits for season 5 show June coming out of the front door with a pitcher of what looks like iced tea, and calling for Ward, Wally and Beaver who are all working outside. But the door opens by itself as she comes out, and then closes by itself behind her. If the entire family is outside, who opened and closed the door?
Other mistake: When the show aired in 1990, in the pilot episode Brenda falls for Jason. She later on reveals herself to be a "16 year old junior" in high school. Season 2 opens up with the gang on summer break which technically would make them going into their senior year. It wasn't until Season 3 that they were going into their senior year. They graduated in 1993 from West Beverly but the show debuted in 1990 so technically they should have been sophomores.
Klink for the Defense - S6-E19
Continuity mistake: General Burkhalter is eating Klink's dinner. When finished he places a metal cover over the plate. In the next shot the cover is lying on the table and there is extra food on the plate. (00:15:25)
Is There in Truth No Beauty? - S3-E5
Other mistake: In the final scene, Kirk is still in the transporter room, but does not have on a visor when the ambassador transports out. Even if he did, humans can still go mad if wearing one and that's why Spock operates the transporter. Spock has his visor on, but then you see Kirk walk out of the transporter room without a visor and he is not going mad.
Continuity mistake: While Tori is getting her mask removed, another shot shows her sneaking back on stage, but the next shot shows her still getting her mask removed.
Gold Is Where You Leave It - S1-E19
Revealing mistake: Buck lights the fuse and tosses the dynamite-filled barrel at the bad guys. We see the explosion. Unfortunately, after that, we can also see the intact barrel still rolling away in the dirt.
Snow Falls - S1-E3
Visible crew/equipment: When the horse carriage is ambushed, just as Princess Abigail can be heard screaming "Please, help me", the camera pans downward and a horse wrangler wearing a blue baseball cap can be seen in the lower left hand corner, hiding behind one of the horses. (00:03:20)
Shoes, Hats, Pickle Jar Lids - S5-E9
Revealing mistake: When Charlie is in the Ferrari, his gets a call from Teddy. When Charlie brings the iPhone to his ear and talks to Teddy, you can see that the iPhone is upside down showing that no one actually called his phone.