Throw It In!: During the climactic chase sequence, Eleanor was accidentally clipped from the rear by another car, causing it to spin out of control and collide with a lamp post. The collision was kept in the film for dramatic effect. Also, the derailed train at the very start of the film was a real one, which Halicki happened to come across, so he incorporated it into an Establishing Character Moment scene.
The 1973 Cadillac Fleetwood 60 Hallicki is driving in the beginning and after arriving at the airport was borrowed from a friend. After driving it at 100 MPH for several stretches, the lifters were loose and hammering. The owner was not happy (most likely the lifters weren't tightened properly to begin with).