The Raffle - S3-E3
Continuity mistake: When the woman is taking the TV, the doors on the shop go from open to shut between shots. (00:17:00)
The Raffle - S3-E3
Revealing mistake: The woman who wins the TV supposedly hits Kenan with it, but very obviously misses. (00:17:05)
The Raffle - S3-E3
Revealing mistake: When Kel is trying to stop the woman taking the TV, he grabs her leg. If you look closely, he hasn't got hold of it at all. (00:17:10)
Continuity mistake: When Kel initially hits the wall with the mixer whilst they're making a cake the picture falls down, however when he chases Kenan over to the same wall with it seconds later, the picture is back on the wall again. (00:14:35)
Continuity mistake: When Kenan and Kel are in the kitchen trying to make the birthday cake, there is a blackboard behind them. The writing on the board disappears and then appears again during the scene.
The Contest - S3-E16
Continuity mistake: During the whole first scene at Rigby's the clock never changes.
Revealing mistake: The graduation stage appears to be set in front of a woodland area. However, when Kel climbs out of the bulldozer after having demolished the stage, you can see that it's actually a backdrop as the rail holding it up is visible.
Aw, Here It Goes To Hollywood (2) - S4-E9
Continuity mistake: When Kenan and Kel are chased out of the shower by David, the clothes that he's wearing are completely dry, despite the fact he was just in a running shower.
Other mistake: When Roger writes the note after Kel glues his mouth shut, Kenan reads back far more than Roger could realistically have written in the short amount of time he took to write it.
Answer: He's simply enjoying doing it himself. Especially since he likely believes he can do it better than she can.