Continuity mistake: When Gus is hiding behind the trees at school, no one is standing behind the fence, but in the next shot, the gang suddenly appears behind it.
Other mistake: When Gus and T.J. are talking on the bench, as Gus says, "No, at least not yet," his watch is missing from his wrist; then it appears mid-shot.
Continuity mistake: When the gang sees Gus standing next to the tree, T.J. has his backpack on, but when the cops arrive, his backpack vanishes. The straps also change from grey to blue.
Bonky Fever - S4-E30
Other mistake: When T.J. goes to Miss Finster to tell her about Mikey's Bonky stuff, Miss Finster's waistband is yellow when it's supposed to be white. Then, when she takes the bag from T.J., it has changed to pink, then turns white and back to pink mid-shot. Her collar is also yellow in this shot, then turns white and back to yellow mid-shot as well.
Bonky Fever - S4-E30
Continuity mistake: When the gang arrives at Mikey's house with his birthday gifts, Gus wears a red bow tie. Then, when the gang walks up to the door, Gus's bow tie has changed to the same color as his shirt, then goes back to red in the next shot.
Bonky Fever - S4-E30
Continuity mistake: When the gang arrives at Mikey's house with his birthday gifts, note the colours of the gifts that Gretchen and Gus are holding. When the gang looks at Spinelli's gift, Gretchen and Gus's gifts have swapped colours, then they swap back in the next shot.
Bonky Fever - S4-E30
Continuity mistake: In the cafeteria, Mikey asks the lunch lady for more pudding for Bonky. When the lunch lady refuses, the clothing on Mikey's Bonky puppet has vanished, then it reappears in the next shot.
Bonky Fever - S4-E30
Continuity mistake: After the gang gives Mikey his backpack full of Bonky stuff, Mikey runs away from them, and he is heading towards two kids playing marbles. Then, when Mikey slips on the marbles, they have changed colour.
Bonky Fever - S4-E30
Continuity mistake: After the gang finds out that Mikey was sucking on a Bonky pop, they find his backpack, which is its usual green colour. Then, when they discover all of the Bonky stuff inside it, it has changed to red.
Bonky Fever - S4-E30
Continuity mistake: When the gang talks about Mikey's birthday party near the start, Gretchen's bicycle helmet constantly changes throughout the following shots. First, part of her helmet changes from purple to blue, then it's purple again and the straps vanish, then they reappear, then the helmet becomes red, then it's the correct colours again and the straps become blue, and finally, the straps change back to purple mid-shot.
Other mistake: When Spinelli's real parents arrive at Parents' Night, the shot is flipped: the potted plant and poster are on the opposite sides, the letter on the poster is mirrored, the door opens the opposite way, and Spinelli's parents are running in the wrong direction. (00:08:26)
Continuity mistake: When the boy in the blue shirt tries to make an appointment for a haircut, the book on Gus's desk is blue, but when the kid leaves, it changes to green.
Continuity mistake: After T.J. and Vince walk out of the school while mocking Mademoiselle, it cuts to a shot of the rest of the gang, and Spinelli is standing behind Mikey. Two shots later, Spinelli has vanished from behind Mikey, then reappears a moment later.
Continuity mistake: When T.J. walks out of the school while mocking Mademoiselle, he is not wearing his backpack, but in the next shot, he is.
Continuity mistake: In Mikey's flashback, when Mikey's father enters the house, he is not wearing an undershirt. Two shots later, he is wearing a blue undershirt under his collared shirt (either that, or his skin is miscoloured), which disappears in the next shot. His belt buckle also changes from dark blue to light blue, and his necklace changes design when little Mikey jumps on him.
Other mistake: When Mikey enters the dance class and Spinelli says, "Mikey?", the letters on the door to Mademoiselle's office are mirrored; the background is flipped in this shot.
Continuity mistake: At the dance class, when Mademoiselle asks where the new girl (Spinelli) is, the girls point to the curtains, and there is a shot of the curtains with a door on the right side of them. Later on, Mikey enters the class through that door, which is now on the opposite side of the curtains.
Continuity mistake: The gang goes to Spinelli's house to ask her about her parents. After Gretchen asks why her parents don't ever come to Parents' Night, Spinelli tries to close the door, then T.J. puts his hand on the door and says, "Come on, Spinelli, we're your friends." In the next shot, his hand is suddenly not on the door anymore. (00:04:46)
Other mistake: When Spinelli's real parents arrive at Parents' Night, as Spinelli's mother tells Miss Grotke, "She just stopped wetting the bed this year," her necklace vanishes, then reappears mid-shot. (00:09:23)
Continuity mistake: At Parents' Night at the school, the doorknob is on the left side of the door to Miss Grotke's classroom. Then, when Spinelli and her "parents" go out of the classroom, the doorknob is on the opposite side, then goes back to the left side in the next shot. (00:07:34)