Continuity mistake: When Bugs dresses up as a Spanish Matador, he is wearing a hat on his head, but when he holds his red cape in front of a water hydrant, the hat has gone.
Revealing mistake: When the dog picks up the stick of dynamite, you can see the stick is not lit, yet it still manages to blow up.
Continuity mistake: When Bugs lights the stick of dynamite, he is holding the stick with both hands. But when we see him peering behind the post in the next shot, he is holding it with one hand.
Continuity mistake: Throughout the race, watch the bands on the dogs. In some shots, they have numbers on them: others they don't.
Continuity mistake: When Bugs emerges from his hole at the start of the cartoon, you can see there is some dirt around the hole, but when we see a close-up of Bugs in the next shot the dirt has gone.
Continuity mistake: When we see "Grandpa's Folly" being 'scratched' in his starting box, the box has no door in front of it, but when we see the boxes at the start of the race in the next shot, a door has suddenly appeared.