I had a burst disk go on me. I was driving from the fill station with a 5lb tank in the back (used for beer dispensing also, mmmmm..) Anyway... tremendous pop and a lot of snow in the car, but not a big problem. I rolled down the window--that's CO2 don't forget...the stuff we EXHALE.
The burst disks are designed not to let any projectiles out and the cylinder will not go flying like in the movies, so don't worry about that. I would avoid hanging around in the car or being directly in the spray (it's REALLY cold), but if it's not sitting in your lap, you'll be OK till you can pull over. Just make sure you roll down the windows 'till you get out.
Good luck.