Visible crew/equipment: When Martin is fighting the "puppy" at the door, you can see a crew member's hand pushing the doorknob open to portray the puppy is trying to get back into the room.
Continuity mistake: When Bentley says how Maple Man can "gobble my knob", he briefly pauses between each word. When Theresa then plays back Bentley's confession, he says "gobble my knob" without pausing. (00:18:58)
Plot hole: In the episode where Gabe wants PJ and Teddy to pretend to be his parents when his teacher wants to see them after getting in trouble at school, it is established that Gabe's elderly teacher is short-sighted. When he asks "How many fingers am I holding up" his teacher gives an incorrect answer. However, later in the episode, his teacher spots Teddy on a date at the cinema (movie theatre) and assumes she's cheating/having an affair. How could she have seen Teddy from a row in-front, when Teddy is facing the audience and not the teacher, if she couldn't see how many fingers Gabe was holding up close to her face?
A Sentimental Journey - S1-E19
Revealing mistake: Dialogue in the episode specifically mentions the A2 and A282 roads near Dartford, Kent - the actual roads used were the A1 Barnet by-pass, Galley Lane and Well End Road. The error is revealed by the sight of a road sign that appears just as the Austin Princess Limousine turns on the the main road - the sign shows that the car is not turning on the the A2/A282 near Dartford, but the A1 at Barnet some 40 miles away.
Continuity mistake: After Mike's mother tells him that she heard a prowler, when it cuts to Mike and Carl showing up at her house we see that the window is wide open, but when they move in closer ordering the "sicko" to come out of the hedge, the window is closed as it should be, until Mike's mother opens it when she sees that the "pervert" is actually Kay. (00:00:55)
Factual error: In the opening sequence when Maddie is supposedly driving from Michigan through Ohio and back to Pennsylvania, you can very briefly spot the reflection of a "TD Canada Trust" in the car window. This is because the show is actually shot in Vancouver. In the United States the company is simply known as "TD Bank", which doesn't operate any branches in either Michigan or Ohio. (00:01:55)
Continuity mistake: When Sam is in the bathroom holding up two sample paint chips, in the first shot she's 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.
Chez Mammy - S3-E15
Revealing mistake: When Cathy and Gaston return to the house to find Betty, Father Damien and Annette Curtain high from the chocolate brownies, she asks where Mrs. Brown is and she tells Cathy that she is upstairs wandering around since she is high. Cathy then tells her to come back downstairs and Mrs. Brown replies a few seconds later saying she is coming back down and flies down the stairs in the chair lift. Before Mrs. Brown comes back down, she can actually be seen sitting in the chair lift at the top of the staircase, from the moment where she tells Cathy she is upstairs to the moment where she says she is coming, waiting for the cue to come downstairs.
Factual error: When the boys are sent back to the Cretaceous era, they come across a leptictidium, a small, bipedal mammal they call "Leppy." Leptictidium were not around in the cretaceous, they didn't appear until around ten million years after the dinosaurs went extinct, in the early Paleogene. They also lived in Europe, not North America.
Continuity mistake: In the scene where Rube shakes hands with the animal protesters, he is not wearing the trash bag while shaking their hands. He is wearing the trash bag immediately before and after. (00:04:45)
Suggested correction: He is wearing the trash bag because one of the posters commits on it.
Other mistake: When Sportacus jumps out of his blimp, his crystal is missing.
Factual error: They used an EpiPen to bring Liv back but they're holding it backwards. The way it's being held, Ravi would have injected himself instead of Liv and she wouldn't be revived.
Advanced Introduction to Finality - S4-E13
Continuity mistake: In episode 11 of Season 4, it was stated that Leonard got an A in 1968, then opted for pass/fail to have the highest GPA in the college. In the final scene of this episode, however, it shows Greendale college as being established in 1974.
Continuity mistake: In episode 64, "For Whom The Bell Tolls. And Tolls. And Tolls", Tracy is shown seated at the table with a bowl of cereal - but in the shots immediately before and after, she's not there, nor is there any food at her place. (00:01:10)
You Wreck Me - S1-E5
Continuity mistake: In the scene at the golf course Bobby tees off as a left handed golfer, in the next scene he is now right handed. The golf glove has moved from his right and to his left and he also takes his shots as a right handed golfer.
Odd Man Out - S3-E6
Factual error: Near the end of the episode when Kevin and Paul are riding their bikes toward each other before they stop for a brief hello of sorts, Kevin rides past a couple cars parked on the street that were built in the early 1980's. A red Pontiac LeMans and a black Pontiac Grand Prix-both were parked in front of the 1969 Ford Thunderbird.
Continuity mistake: Roy closes his comic and throws it onto the desk. The camera flits back to Moss, then back to Roy, and Roy is holding the open comic again and repeats the same actions. (00:06:25)
Continuity mistake: After Rachelle gives Ethan her makeup bag, Ethan is holding it to his side with one hand. After it zooms in on him, he now is holding it with two hands in front of him. (00:18:20)
Continuity mistake: When the Polaroid photo is shown of Betty and Walter with his boss and his wife, Betty's hands are behind Walter and the boss's wife's back. When it was taken, her left arm was out and her hand was on her own leg.
Continuity mistake: The first four episodes of season two have absolutely no continuity with the show. Prime examples are the fact that Shendu exists again as a statue which had been confirmed to be destroyed in "The Day of the Dragon", the final episode of season one. Next during "The Warrior Incarnate" it is mentioned that not all the talismans were in fact present, such as the dog talisman, when all talismans must have been found, or the events that escalated during the final episode of season one would never of happened. This problem is the extended during the next episode where Jackie Chan discovers the snake talisman in some sort of Brazilian temple - he had already learned of the snake talisman by stealing it from the museum quite early on in season one. The final continuity error is that Tohru goes from friend to foe and then back to friend as if the first four episodes of season two never happened.
Suggested correction: These were "flashback" episodes, not "they never happened" episodes.