When Alan Holiday busts through the door that connects the two rooms together (while the police are waiting outside), the door that leads to the hallway is closed. In the previous shot, the door was open with the police banging on the door.
After the British police decide to fly to Dunkerque Alan Holiday hears the tug-boat horn and looks out of one of the windows of the train. He gets a clear view of the back of the tug (the "Gaillard") which would not be possible from his vantage point inside the train which is itself inside the ship. The shot is obviously taken from a jetty - the mooring lines of the ferry are clearly visible.