Continuity mistake: As Bart is about to enter his house after trying to impress his friends by krumping, you can see he is entering the front door. However, in the next shot when he gets inside and Marge is waiting you can see that he has entered the family room, which is only accessible through the back door. Entering by the front door would place him by the stairs, at the front of the house.
Continuity mistake: When the school bus drops off Bart and Milhouse at the Simpson house, Bart puts his backpack on frontwards and starts krumping. When he walks through the front door, he is still wearing his backpack on his front. It then cuts to inside the house, and we still see him coming through the door, but the backpack is gone.
Continuity mistake: When the men from Festival Cruise Lines arrive at the Simpson house, they park in the left-hand lane (closest to the house) with the car facing oncoming traffic, seen both when they first pull up and, more, in the background while informing Milhouse about his parents. But in the overhead shot of the house, the car is parked the other way around, following the direction of traffic.