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.
The New Kid - S1-E2
Continuity mistake: In the beginning, after the kids have gone to recess, Vince starts talking to TJ about Gus. The number of bricks between the windows on the wall behind them and the bricks' position changes four times.
Continuity mistake: When Mikey's music teacher gets engaged to the Spanish guy, her ring disappears between shots.
Plot hole: Whenever Gretchin calls Mikey up to the stand to explain what he saw, he says that he had followed Spinelli and Randall to the wooden fence, where he Saw Randall on his knees in front of Spinelli, begging for forgiveness, then Mikey began running to the other side to stop Spinelli from pummeling Randall with the "rock" but didn't make it in time. We then later find out that Spinelli had actually rescued Ms. Finster's cat out of a tree and Randall hit himself with the rock out of spite. But it is impossible that Spinelli could have given up on hurting Randall, climbed up a tree, rescued a cat, climbed down, handed the cat back to Ms. Finster, gotten praise from Ms. Finster, then have Randall attempt to pick up a big rock, then get a smaller one and hit himself with it in under 3 seconds (the duration of how long Mikey ran before he heard Randall's scream).
The New Kid - S1-E2
Continuity mistake: In the beginning, as Gus' dad walks away, the A/C duct goes way down the hallway, and one side is halfway in one tile and the other side is halfway on another tile. When Gus is talking, the duct is much shorter, and the whole duct is contained in one tile.
The New Kid - S1-E2
Other mistake: At the start when the gang change the time on the clock in the classroom, it wouldn't control the main school clock, plus in every other episode the clock has been operated by The Box on the side of the school, as shown in " The spy who came into the playground".
The New Kid - S1-E2
Continuity mistake: Near the beginning, after King Bob declares Gus as The New Kid, the kids are cheering and TJ and friends have disappeared from the shot. Then Gus looks down in front of him and the guys are right there in front of him.
The New Kid - S1-E2
Continuity mistake: In the beginning, as Gus' dad walks away, there is a sign on the door to the right that says "Boys." I would assume this is a restroom. Then, two shots later, it shows Gus from his front and in place of that sign is a window.
The New Kid - S1-E2
Continuity mistake: When Gus' dad introduces himself, he says he's in the USMC (US Marine Corps). In the rest of the episodes, he's in the Army.
The New Kid - S1-E2
Continuity mistake: When Spinelli says, "Roger already, let's get this show on the road", there's a puffy cloud under "Good" in "Good Morning Gus". When Gus is in the bus and notices the billboard, the cloud is pushed in on the upper left part of it.
Audio problem: After "Peanut Butter Kid" retrieves the baseball Vince hit (presumably all the way to China) Spinelli screams rather loudly. However her lips don't move when she does.
The New Kid - S1-E2
Continuity mistake: In the beginning, right as Mrs. Grotke asks for Gus to describe his "personal journey", there is a short kid with a white t-shirt and dirty blonde hair, with the globe behind his head. As the kid asks if they can go to recess now, the globe has moved way to the left.
Continuity mistake: The kid who says "Dumb 4th graders..." IS a 4th grader. Watch the beginning of "The New Kid" and you can see him in Mrs. Grotke's class.
Continuity mistake: When TJ is in The Box, he lays down and puts his head on his baseball glove. Then when he gets up, he doesn't pick it up, but it's nowhere to be seen. Then a couple of shots later, it's back, and it's on the other end.
Factual error: At the end when Ms. Finster tells Randall to give her the names of the kids involved with the ball incident, she says to list them in alphabetical order. The first name Randall says is "Dettweiler, T.J." But "Blumberg, Mikey" would actually come before that, and given what we know of Randall, this isn't the kind of mistake he is likely to make.
The New Kid - S1-E2
Continuity mistake: In the beginning, as Gus' dad walks away, the lights on the ceiling are 3 tiles apart. However, while Gus is describing his "personal journey," the lights are two tiles apart.
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 Vince's family is eating dinner, Chad's bow tie changes at least twice from red to black.
Other mistake: In the episode, "the peanut butter kid", he is always eating his sandwich and it always seems like he only took a bite out of it and sometimes it went all the way back to the top. How could that be, he couldn't be chewing the entire time.
Speedy, We Hardly Knew Ye - S1-E10
Factual error: Near the middle of this episode, Gretchen says hamsters don't hibernate. They do, it just depends on the time of year and if it's a wild hamster.