That's pretty funny. But had there been a car, camper, boat, etc., parked there, or had a pet or person been in the line of fire, that might have had some consequences! Probably something sticky in the bottom of the trash can made the bag stick well enough not to drop into the truck, but didn't have enough holding power to deal with the fling at the end of the dump. It might be that the truck should be programmed to execute a somewhat slower movement after the dump-and-bang phase of the operation. It would cost a bit of valuable time, but might be worthwhile from a liability perspective.