Jason Bruce Robertson utilized his 1968 Chevy Camaro SS, as requested due to the need for "older" vehicles. However, it was cut from the film due to continuity issues, with the film supposedly set in the 1950's and not the late 1960's.
In the final scene with the national guard posted outside the administration building, the air conditioners which are placed prominently in two front windows are certainly not the type or size of air conditioners in 1957.