Continuity mistake: In this episode, it shows Randall in Miss Grotke's class, but in every other episode, it's never shown him in there.
The Legend of Big Kid - S1-E14
Continuity mistake: At the end of the episode, when the gang is caged, right after Vince gives TJ the baseball card, TJ's facepaint turns from blue to red, then back to blue. (00:08:35)
Continuity mistake: When Gretchen is playing with Cornchip Girl, she puts down a card which is the orange cheetah. but after she has talked to TJ, it has suddenly changed to a completely different animal.
Continuity mistake: At the very beginning, Gus drinks his entire carton of chocolate milk. Then in the wide shot, his carton is white. Back to a close up, and it's brown again.
Continuity mistake: When TJ makes the morning announcements, in the first scene of the classroom we see a boy in a blue hat sitting in the back row. After TJ says that the kids can refuse to answer a teacher, the same kid is suddenly sitting in the second row so he can slap hands with someone in the first row.
Continuity mistake: When Vince's family is eating dinner, Chad's bow tie changes at least twice from red to black.
The New Kid - S1-E2
Continuity mistake: In the beginning, Gus' dad steps aside to reveal Gus behind him. Then, he says, "Well, my duty here is done. Mrs. Grotke, boys and girls," and then salutes them and walks away. He has moved back behind Gus. He had no time to move to that position.
Continuity mistake: When Library Kid sees her kindergarten class, she's wearing a dress, but when she runs into the library, she's wearing a T-shirt and skirt.
Continuity mistake: When TJ comes to school in the morning and everyone starts cheering, we see two Ashleys clapping with everyone else. As the camera follows TJ as he walks to the entrance, we see the same two Ashleys a second later.
Continuity mistake: After Mrs. Finster has her show of strength and is pulling Gus away, he still has the chains from the wheel on his arm. When the shot changes, the chains are gone.
Here Comes Mr. Perfect - S4-E18
Continuity mistake: When Jared is talking to the whole school about shunning him, his undershirt changes from white to blue to white again.
Continuity mistake: When Menlo tells the crew about Randall's joke book, he loosens his tie, and it's still loose when he says "Indeed." But half-a-second later, as he walks away, his tie is back to normal.
Continuity mistake: When the gang is playing marbles, there are seven marbles in the ring, with three black ones on the left and four orange ones on the right. In the next shot, there is suddenly a green marble on the right side of the ring, with a black marble next to it.
Mama's Girl - S2-E14
Continuity mistake: After Miss Grotke avoids the mud puddle, a kid says, "Spinelli just called Miss Grotke Mama!" In this shot, Ashley Q is near the left side of the screen, Ashley B is near the right, and the other two Ashleys are nowhere to be seen. In the next shot, all four Ashleys are suddenly shown together, laughing.
Schoolworld - S4-E21
Continuity mistake: When Gus gets locked out of the school after recess, he asks SAL to open the hallway door. He looks up at the clock, and the time on it is 10.46.05 (then goes up to 10.46.08 by the end of the shot). A few seconds later, the time changes to 18.46.16, then 10.46.17, then 10.45.18.
Continuity mistake: When Randall begs Gretchen to do his homework, Mikey says, "Tutoring is just another word for helping," and his backpack is green. A few seconds later, it changes to blue.
Continuity mistake: When the marble gets knocked out of Spinelli's hands and it falls into the drain, the marble approaches the hole to the very left of the drain, but in the next shot, it falls into the hole right next to it.
Continuity mistake: When Dr. Quilty is filming Gretchen in front of the Kindergarten Area, Gretchen puts some candy in front of the door. When Gretchen runs away, the candy has vanished.
Continuity mistake: When the kids are fighting over the can at the celebration, the can keeps swapping between green and red between shots. There is also one shot where the can is red but turns green twice in two frames.
Spinelli's Masterpiece - S4-E27
Continuity mistake: When the kids are all on the jungle gym to see Spinelli's drawing, Jerome can be seen sitting on the bar of the swings. However, when everyone is cheering he has suddenly moved to the ladder.