Pop Me and We Both Go Down - S1-E10
Continuity mistake: In the episode "First Kiss," Justin has a girlfriend, Miranda. But in this episode Justin starts dating this new girl from his class, who's actually the same Miranda. This doesn't make any sense. How is she a new student and how could they just meet if they were dating eight episodes ago?
Other mistake: At the beginning, when everyone is watching Shelby fighting on TV, the timer is going too slow. According to the timer, the fight ends at 2:53, which is only 7 seconds of fighting, yet the fight was way longer than that.
Pooh's Double Trouble / Eeyore Sleeps on It - S1-E19
Factual error: The letters and symbols on the characters' reflections in the mirror look like their regular counterparts, when they're supposed to be in reverse.
Sky: Part 1 - S5-E1
Continuity mistake: The baby carrier little Sky is in as the group heads towards the car changes between takes. When they are walking down the driveway, it is open, and Sarah Jane quickly closes it when Gita comes up. Gita opens the carrier, to discover the baby, and Sarah Jane closes it again. There is more dialogue and Gita goes back to cooing at the baby. When did the carrier open again? Then the car alarms go off and if you look closely, you can see it's closed again, which is confirmed when the baby is handed off to Clyde.
Smells Like School Spirit - S1-E7
Continuity mistake: In the scene where Newt is going to measure for the "Chill Zone," he asks Cory to help him. At first Cory is holding the main piece of the measuring tape, while Newt runs out with the "pull out end." Shortly, after cutting out to a conversation, Cory is holding the "pull out end" and then releases it, so his buddy Newt is the one caught by surprise when Cory releases his end of the measuring tape.
The Thrice Cream Man/The Flibber-Flabber Diet - S1-E7
Other mistake: In "The Flibber-Flabber Diet," Chowder and Truffles return when Mung calls them. How could they hear him when they'd already left?
Race to the Spaceship/Sandbox Surprise - S3-E5
Revealing mistake: In the sequence where Pig is making a pizza with strange toppings, an ant caries a large bucket of popcorn up the counter. It is flush on its back with no top when on the floor, and the popcorn is bulging out. The ant turns 90 degrees and walks up the counter, and the popcorn thus turns on its side in the air. Not one piece of popcorn falls out or even shifts, despite the pile now pointing out rather than up.