Popular Science has a breakdown of the physics:
"If, as the narrator informs us, the car achieves a takeoff speed of 280 mph, then using the equations of projectile motion, we can easily calculate that without air resistance (estimating a launch angle of about 30 degrees) the maximum distance the car could achieve is around 1500 meters, or just short of a mile. (I'll leave it to those of you with a little physics background to confirm this is true.) However, at speeds of this magnitude, air resistance will have a major effect on the flight of the car. The force of air resistance is proportional to the square of the velocity, so if you double the speed you quadruple the air resistance. Incorporating the effect of air drag into the calculations we find that Kenny won't even make it a quarter of a mile before falling ignominiously into the river."
Ooo. A little harsh. Come on guys, hind-sight's 20-20 right? Anyway, check out the video and judge Kenny's physics for yourself:
Further reading: For those unfamiliar with the psychology of the male Canadien and/or interested in further exploring Canadian anthropology through the miracle of YouTube Video, see also The Best Of Ron Hextall, Canadiens vs Nordiques 'Good Friday brawl' 1984, The Never-Ending Bench Clearing Brawl of Canada vs Russia 1987 at the World Juniors, the seminal National Film Board of Canada mockumentary "FUBAR", and Canadian television favorite "The Trailer Park Boys".