"Mary Sue" explaining the... um... rules of the bedroom to her mother, and the resulting scene.
Fire! Fire! Fire!... Cat?
David/Bud showing the firemen (who never put out fires, only rescue cats from trees) how to put out the tree on fire by turning on the firehose.
Fireman: Huh, so that's what these things do!
David/Bud finding out the rules of Pleasantville means that every basketball throw goes through the hoop. So he turns away from a hoop and kicks the basketball. It bounces off the wall and the roof and then swishes through perfectly.
The rest of the team suitably freaks out after their world, and themselves, have unknowingly changed (thanks to Skip telling them what Jennifer did to him) and they all miss their simultaneous practice shot, complete with the coach telling them to back away from the balls ("Don't touch it, boys!")
"You can't do this! YOU CAN'T DO THIS TO SOMEONE WHO DOESN'T EXIST!"
"We're supposed to be at home, David. We're supposed to be in colour!"
When George arrives to an empty and power-less house, the poor guy is utterly befuddled.