I placed a fire inside of a barn with minimal windows. The barn has two narrow slits on either side of it's 2 doors and other than that there's really no other place where the light would emit from the building. However, I wanted to see how visible the fire would be when approaching the building from a distance, and I noticed that the light is completely visible almost as if it's outside. It seems like the light will remain visible if the area has not fully rendered. You can see the reflection of the fire off the trees and everything as if the walls and roof of the building were not even there.

This breaks the game and gives away your position from a great distance.