The film is loosely based on an experience from the Director's past. In the early eighties, while he and a few friends were driving home, they were chased by a car, for several hours, through backwoods roads.
Spoiler: In several scenes, a black '57 Series 62 Sedan is substituted for the Series 75 limousine. Since the roof and rear window is completely different on the two cars, a fake roof extension had to be created for the Series 62 model. It was this car and not the limousine that drove off the cliff into the frozen lake at the end of the film.