At the end of the movie when Jonathan loses it and starts smashing into Kenny's red '55 Chevy, they take off down the street ramming each others' car. Kenny crashes into the passenger side of Jonathans' Studebaker not once, but twice. Yet when Jonathan wheels back to the curb to talk to the ugly-duckling-turned-swan-girl, the car has no side damage at all.
This movie was supposed to be set around 1956. In the beginning of the film, Gene and Jonathan are outside the school and Gene is trying to teach Jonathan how to be "cool." Right after that, they go into the school and a tune by Chuck Berry called "School Days" begins to play. That tune by Berry was not released until 1964!