The only way to lock the car without the key fob is to use the lock button on the drivers door, which only works with the door shut. You would have to reach thru the window or top from the outside to lock it without the alarm. I'm not sure how you would "accidentally" open the door with the alarm on, as the outside door button is deactivated with the alarm armed. You would have to reach in the car and use the inside door handle to open the door.