Revealing mistake: Kel is in the Orange Rain and if you look at the road you can see it is just paper by the way it warps. (00:09:50)
Visible crew/equipment: When Kel is singing in the Orange Rain you can see stage lights reflected in his umbrella. (00:10:00)
Continuity mistake: During the filming of "Supermarket Cop 3," the time on the clock changes throughout. (00:18:00)
Continuity mistake: Roger is building Kyra's castle out of sugar cubes. He starts to put two cubes on top, but then the cubes changes from two to four and then back to two again in the next shot.
Answer: He's simply enjoying doing it himself. Especially since he likely believes he can do it better than she can.