For the entire film, Sgt. Marcam's CHP cruiser is a then-new 1976 Dodge Monaco (an intermediate sized car). For the crash sequence at the end of the film, his car changes into a much larger 1973 Dodge Polara (no doubt a budget consideration, as the car is wrecked).

The opening credits state that the movie was "based on the novel 'Expressway' by Elleston Trevor" (a pseudonym of Trevor Dudley Smith). Smith did write the book, but it was published under another of his pseudonyms - Howard North.