When the instructor gets into the car, Michael's left arm is propped up on the open window, then it cuts to a close-up of him as the instructor comments on his mask and Michael's left hand is now on the steering wheel, but when it cuts back to a wide shot, his arm is propped up on the door again.
When Michael stabs the driving instructor, he tells him it's a $50 fine for assaulting a DMV (Department of Motor Vehicles) official, yet in Illinois, where the film is set, it's called the Vehicle Services Department.
Despite being set in 1978, modern day (2012) cars can be seen on the road.