Continuity mistake: When the President is in the shop and the tower of Orange Soda is about to collapse, watch Kenan. He puts his arm through the display to make it collapse.
The Cold War - S1-E8
Continuity mistake: The clock in Rigby's is changing time throughout. (00:04:00)
Who Loves Orange Soda? - S2-E4
Continuity mistake: When Kenan and Kel are making the bet, the clock on the wall changes time. (00:08:00)
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
Continuity mistake: When at Rigby's at the start, the clock is constantly changing time. (00:02:00)
Continuity mistake: In the episode when the president comes into Rigby's, near the start Kenan fixes the slush-o machine, but it doesn't work, and slush-o sprays all over Chris. Afterwards, one of the slush cups on the counter falls over. After that, the cup keeps on vanishing then reappearing.
The Lottery - S2-E3
Continuity mistake: Kenan gets the tickets for him and Chris from on top of the machine not from the machine. (00:08:50)
The Lottery - S2-E3
Continuity mistake: When Kenan is putting the cans on the counter at the beginning, the cans swap places. Watch the green one. (00:03:30)
The Lottery - S2-E3
Continuity mistake: When Kenan is getting a ticket for Kel, he goes to put it in the machine but misses. The next frame it has disappeared. (00:09:35)
Continuity mistake: Cold War: Kenan holds the melon with the holes facing down. Yet no juice comes out, but it does when Chris looks at it. (00:04:05)
Continuity mistake: Bloodbath's lead disappears between Kel bringing him out and him chasing Chris a few seconds later.
Continuity mistake: When Kel throws the foot dust the first time, a girl at the back is coughing despite no dust meeting her.
Doing Things The Hemingway - S1-E3
Continuity mistake: When Kel jumps into the window cleaners' bench it's only a fraction down from the roof. no more than 6ft. Next shot with Kenan the bench is further down.
Continuity mistake: Cold War: At the very start it is clear that Kel does not spit out the mouthwash into his hat. This is confirmed by when Kenan throws it no liquid can be seen.
Continuity mistake: When the President is being crushed in the Oval Office, Kel opens the sliding door. The door stays open but when left alone Kenan and Kel go to look at it and it is now closed.
The Contest - S3-E16
Continuity mistake: During the whole first scene at Rigby's the clock never changes.
The Raffle - S3-E3
Continuity mistake: Chris comes into the shop and the clock says 8:55. He states the draw will be in 20 minutes, however, at the draw the clock still says 8:55. (00:11:00 - 00:12:00)
The Lottery - S2-E3
Continuity mistake: The Lottery numbers change from the draw to when claiming.
Continuity mistake: There is a 5 minute scene in Rigby's at the end but the clock doesn't move at all.
Answer: He's simply enjoying doing it himself. Especially since he likely believes he can do it better than she can.