Ah, ok, if you turn off Buena Vista Dr. onto Epcot Resorts Blvd, you have the Boardwalk on your left and the Hess on your right. You can make a left to go to the guard booth, or you can go straight a little further on Epcot Resorts Blvd and a little further on the right it seems there's an entrance to a large parking lot.
I can remember a long time ago parking for dinner at the Boardwalk and the guard booth directed me to this large lot across the street (across Epcot Resorts Blvd).
If this is an employee lot, perhaps they were just very busy that night years ago and used the employee lot, and put the gates up permanently for the night (which is why I don't remember gates).