Vehicle moved away backwards after placing vehicle in park. Vehicle is in a repair shop in Calgary, Alberta, Canada. Driver's door, door frame, and rear door damage. After placing the vehicle in park following pulling the vehicle forward in drive, I stepped out of the driver's door and the vehicle began moving backwards. I was nearly injured as the open driver's door was bent 180 degrees around as it struck a building support column. I made it partially back into the vehicle, just clearing the door-column squeeze, one leg in and one leg still on the ground trying to get on the brake as I slide past the support column in the drivers foot well. I fell out once past the support column and the vehicle continued to travel backwards another 10 feet or so before striking a tree. The Mercedes Benz dealer in Calgary gave me a copy of a recall notice for Sprinter vans. The dealer informed me Sprinter vans apparently have the same shifter components as the Metris vans. The recall notice was for Sprinter roll-a-way situations following placing Sprinters in park, and do-not sell/drive orders were apparently issued. A police report was taken, but no one has inspected the issue or components. No symptoms or warnings were observed prior to the incident.