Sex scenes between James Ballard and his secretary were filmed but cut because director David Cronenberg felt the actors' chemistry was too good, contravening the nature of all the other relationships in the film.
In a 2020 interview, David Cronenberg stated that he believed Francis Ford Coppola, the jury president at the 1996 Cannes Film Festival, was so vehemently opposed to Crash that other jury members in favor of the film banded together to present Cronenberg with a rare Special Jury Prize. So great was Coppola's distaste for the film that, according to Cronenberg, Coppola refused to personally present the award to the director.
David Cronenberg's agent thought that directing this movie would ruin his career, and begged him to instead direct The Juror (1996), which he'd recently been offered. Cronenberg declined, made this movie, and got a new agent.
In the United Kingdom, The Daily Mail newspaper led the calls for the film to be banned with a front page headline reading, "Ban This Car Crash Sex Film." To cover themselves against possible prosecution, the BBFC consulted a QC to determine whether the film contravened the Obscene Publications Act, a psychologist to see if it could potentially incite copycat behavior, and a group of disabled people to see if the character played by Rosanna Arquette would be considered offensive to them. After all three consultations proved to be unsuccessful, the BBFC were able to pass the full unrated version completely uncut.
In the novel by J.G. Ballard from which this film derives, Vaughan's goal is to achieve sexual climax by crashing his car into the limo of Elizabeth Taylor and gruesomely killing her, a plot item not retained (obviously) for the film.