 FACT: Jack steps off the moving bus at the airport via the rear  doors, since there are no front door steps, and they stay open  afterwards until Stephens steps into the opening. Annie could not  have operated the door switch as would be done at a normal stop,  since this would also have applied the buss brakes; therefore the  doors should close themselves as soon as they are not being held (as  we see them do a few minutes later during the setup for evacuating  the bus).