"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 those are for.
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.
"You can't do this! YOU CAN'T DO THIS TO SOMEONE WHO DOESN'T EXIST!"