General goofiness
The Holes Easter Egg is about 52 minutes into the film in one of the flashbacks to the town that used to stand on the site of the detention center. The town's people have just set fire to the school house and the blond school teacher runs out of the drunk sheriff's office after he tries to kiss her. She runs down the board sidewalk past a store that has a sign above it that says "Guns and Powder". The "Guns and Powder" is reversed like in a mirror.