Very interesting, I wonder if there were multiple points to enter/exit at one point in time. Underneath the station back where the door is in that photo, there is an area about 15 feet back that looks like it may have been an alternate pathway into the fort at one point in time, but it has since been covered up. Kind of like the walkways that are above the station, but with boarding covering it from the outside. Is it possible that is was once open to guests, or maybe was considered as an entrance but closed off before opening?
If it was ever used as an entrance or exit, it would have lead to the garden area underneath the Mine Train, adjacent to the current exit stairway.