I image you could massively troll on our intercity trains by continuing to open the door before they are all shut. Because they are manual slam doors, the guard has to make sure they are all closed before the central lock goes on. So if you were quick, you could could keep opening doors at random until you got removed from the train.
Obviously, if you tried this on a Paris Metro train, you'd lose a limb. Those doors don't give a shit.