The first three scenes in the movie, ignoring for a moment the power of the opening credits sequence, has been a triptych of lust, sex, and desire.  Within the narrative this explodes into a orgiastic display of violence.

The opening sex scenes introduce us adequately to a couple whose moral compass is not only wayward of convention, but also portrays a boredom with even the extremes of most of our natures.  Casual encounters with strangers in open spaces, public spaces, and the slow lazy intercourse as Ballard and Catherine exchange stories of their experiences in a matter-of-fact manner, tell a story.  Through this we know the central characters of the film are going to challenge our ability to empathise.  And this is our starting point! 

However, how does this tie into a love of cars and sex?  In "the accident" we experience the true beginning of our characters story.  Previous scenes lay a foundation of who these people are, and where they stand today.  It lays out the foundation from which the Crash experience will grow.

The central themes of this scene are carelessness, violence, the sculpting of flesh by technology, death, and sex.  This is the moment that sparks both Ballard and Catherine (although she is not in the car at the time of the incident) into the world of Crash, of Vaughan, Remington, Seagraves, and Gabrielle.

The opening of the scene is significant in several regards.  Firstly, note Ballard's relationship to his vehicle.  As the car barrels down a rain swept road, he's trying to read a storyboard for a road safety commercial he's producing.  He is not paying attention to his driving (hence his accident).  Papers are strewn across the floor (we see this later and note they include various bits and pieces of pornography).  In other words, Ballard is not engaged by the vehicle at all, we can assume that his general thoughts are that a car is merely there to get you from point a to point b.

Of course, we all know this is about to radically change.  The accident isn't simply a physical event, but also a savage mental readjustment.  After this sequence, Ballard's relationship to cars is completely changed.  While it's clear at the outset that he doesn't have a personal relationship with his vehicle, once he has moved through the event, he will become attached not only to cars, but to this car.  Later in the film, once he is well enough to drive again, we find he buys not only a new vehicle, but exactly the same type of vehicle. 

Ballard's car crosses the central reservation into oncoming traffic.  Fortuitously, he avoids the first approaching car, hitting the second.  One realizes that the entire movie from this point hinges on this bit of luck.  If he hits the first car, who knows what would have happened?  Perhaps Ballard would have died?  What are the chances that the people in the other car would also willingly become involved in Vaughan's world?

At the point of impact there is a threesome of violence (love triangles seem to be a theme of the film).  In one car we have Ballard, in the other Remington and her husband.  It is Remington's husband that is ejected through the windshield of his car, flying through the air, grabbing at the car emblem, before landing unceremoniously in the passenger seat of Ballard's vehicle, dead.

Ballard and Remington, on the other hand remain relatively unharmed.  In a nod to the road safety propaganda mentioned later, the two survivors are clearly shown wearing seatbelts.  This is perhaps the final nod to car safety we have in the film (later we find that Ballard can no longer stand wearing a seat belt, and we see him tearing it off, as does Catherine in the final reel).  It suggests Remington's husband was not wearing a belt, and had therefore died while others survived.

Both Ballard and Remington are dazed, yet cognitive.  On the one hand Ballard is shown as being in shock.  However, one can suppose that the look on his face isn't simply concussion, but rather the effects of a light coming on, of a door to somewhere unexpected opening.  He looks at the victim in his passenger seat almost nonchalantly, but when he glances through his broken windshield toward Remington, the look we see is not simply shock, but is one of wonder.

The final shot of Remington's husband is a close up of his hand.  His trajectory has carried him out of his own car, through the windshield, and into the passenger seat of Ballard's vehicle.  During this journey his right hand has struck the car insignia on the front of Ballard's vehicle, leaving a large bloody welt.  This picture will return later in the film as Vaughan asks Ballard to get a medical tattoo.

The idea of cars accidents as sex quickly follows, as Remington grabs at her seat belt in order to free herself.  As she pulls it aside, her left breast falls from her bra.  Ballard looks on as though stunned at what he is seeing, and more importantly, feeling.  The connection, both sexual and related to fate, is made.

We experience a crash as something other than simply a destructive force, this is the start of a new life for Ballard and Catherine.  It opens vistas of new emotional possibilities which they accept and adopt quickly, having already been shown to be rather vacuous and bored of the current state of their sex.  Once the accident takes place, and Remington's husband meets his death, the affair between Remington and Ballard immediately begins.  However, it's not an exclusive affair, instead it's an affair with the new world, to coin a Cronenberg term, with the new flesh.

Remington’s husband, in this brief moment, is extinguished.  There is no room for him, for reminiscence or remembrance, after this scene.  In fact, we never even get to know his name.  The Crash event is what lights the fire, and what has come before simply isn’t important, all that matters is this specific event, and the effect it’s had on individuals, and both of them as a collective.