There are two minor bugs in the subway:

1.) When the train stops the door opens rapidly at first, then closes again, and opens slowly the second time for the player to get in - this looks strange

2.) If a player stands too close to the train and gets hit by the door either the first or second time, it closes and never reopens. You have to wait for the next train.

Of course every player has gotten used to it but for new players it can be disturbing. The door should not have a collision value in my opinion so that it opens always.