Continuity mistake: In the introduction, when TJ pulls the ball off Gus, Gus is covered in gum. When they are walking into the school, the gum has disappeared.
Deliberate mistake: Lily was an infant for all of season 5, but beginning with this season, she is around 5 years old. The show didn't jump forward in time, because JT states in a season 5 episode that he is 19, and in the episode this season where he and Rich go to Mexico, he states that he is almost 20, as well as Al and Mark are both still in high school.
My Sister, the Homemaker - S5-E12
Visible crew/equipment: At the beginning of the episode, Jeannie is talking on the phone by the stairs and her sister is hiding behind the banister. Her sister stands up for a moment and shows her full face, revealing that it is actually Barbara Eden's stand-in wearing the green costume.
Other mistake: Michael is 40 in Season 2 ep. 20 (Papa Said Knock You Out) while Jr. is 16 in ep. 19, which could not be possible since he had him when he was 16/17ish himself.
Revealing mistake: S9 E1 "Bully for Ben": When Ben hits the punch bag sideways, it's easy to tell that someone is controlling the punch bag as it never slows down.
Continuity mistake: Chase gives Zoey a radio in this episode, but in 1-3 Webcam, when Zoey, Quinn and Nicole are in Zoey's room trying to figure out who is telling the girls' secrets to people, you can see that radio above Zoey's head.
Continuity mistake: When Kelly is putting the number card on Logan, you can see one on Kendall behind him, when he shouldn't have had one yet.
Archer Vice: Southbound and Down - S5-E5
Factual error: When the bikers are chasing the bus, one of them crashes into the "Now Leaving Texarkana" sign. However, shortly before this, we see Cyril crashing into the sign reading "Austin. 105 miles." Texarkana is almost 350 miles from Austin.
Father Frank, Full of Grace - S1-E12
Continuity mistake: When Steve gives Fiona the ticket to Miami he says it is out of O'Hare. When he goes to the airport he is at Midway.
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: Farzad JinJi is introduced as Dominque in the first season, but he appeared as a different character in the second episode.
Factual error: Wanda's father opens his briefcase of DVDs and one of them is Malcolm in the Middle. But the bomb that killed him fell in 1999, and Malcolm in the Middle didn't start airing until 2000.
Continuity mistake: When Samantha is in the bathroom holding up two sample paint chips, in the first shot Sam is holding up the yellow in her left hand and the blue in her right hand, but in the next shot they've switched and are in the opposite hands, just as Jay arrives with the coffee.
Revelations - S3-E6
Continuity mistake: When Tim puts Lucy in the squad car after "arresting" her, the rear door on the driver side is open, but when the camera pans back to her it's suddenly closed without making a sound.
Revealing mistake: When Brad wears the sunglasses and holds the pole, you can easily see the string that holding it up.
The Burning - S9-E16
Continuity mistake: At the beginning of the episode, when Puddy is farewelling Elaine on the street, he is standing on the sidewalk and leaning through the driver's window. The following shot when she pulls out quickly, you can see through the windows of the car that Puddy is nowhere to be seen.
The Mothers - S3-E17
Plot hole: When the "refrigerator" falls on Tobias's mom, the boys are watching from a side view. It is later revealed that the fridge was just a cardboard cutout. The boys were watching from the side, so how did they not notice it?
Continuity mistake: Sometimes Ed's fireplace in his office is on the right wall but then other times it's on the left. Plus Ed and Mikes' offices switch sides mid series. Ed's office is stage right in early years, Mike's is stage right in later years.
Character mistake: When Grandad collapses, the Doc calls Morwenna's grandfather Mr. Dunwich, which is the surname of one of his patients in this episode. The grandfather has the same surname as Morwenna, which is Newcross.