I put the car in reverse and released the parking brake. The car started to move backwards. However, the back passenger door was wide open, and the passenger was standing outside the car in the path of the open door. The door hit a guide wire running from the top of a power pole to the sidewalk beside the car. The wire pulled the door backwards, destroying it. This was fortunate. Without the wire in the way, I would’ve had not heard the crashing of the door and would have continued to drive over the person standing beside the car as the passenger door knocked him down. The indicator that the door was still open is so small on the gauge cluster that I couldn’t see that the door was still open when I put the car into reverse. There was no audible warning that I was about to move before all doors were closed, and the emergency braking didn’t stop the car from moving. The passenger’s leg got pushed sideways under the open door. Had the guidewire not pulled the door backwards and caused so much noise that I stopped, the door would’ve broken the passenger’s leg and potentially pushed him under the rear passenger side tire.