It should be noted that when Bart & Lisa were put on the rotors of a plane, the plane is a Boeing B-29 Superfortress, the plane that bombed Hiroshima and Nagasaki.
When Bart is driving a lawn mower and is pulled over by the police, Chief Wiggum is driving one of the police cars, even though he's inside telling Homer and Marge about sending Bart to military school.
When Lisa looks down from the Eliminator, the platform under her disappears.
When driving to Rommelwood, the car is Homer's Pink Sedan. However, upon leaving, it is the Orange Station Wagon. Later on, when Bart and Lisa graduate from the academy, they leave in the orange station wagon. On the road, it is the pink sedan, however. Later, when it turns out Homer and Marge were taking them them to the dentist rather than Disneyland, it's the orange station wagon again.
Even though all the glass in Springfield breaks after Bart's megaphone prank, the glass in Chief Wiggum's police car and Homer's car don't.