When Kelso buys his MG Midget (s6e11, "I Can See For Miles") and parks it in the Formans' driveway, it has no luggage rack on the trunk lid. In this episode, when Kelso drives Jackie to the bus station, her suitcase is on a luggage rack on the trunk lid.
In the final scene, Eric tries to drive away but the Vista Cruiser won't start. Everyone gets behind the car and they push it forward. Vista Cruisers were equipped with automatic transmissions. Cars with automatic transmissions cannot be push-started.
At the end of the episode, as the Vista Cruiser is being pushed out of the driveway, it clearly has no windshield and no rear-view mirror.