This question involves major spoilers for The Witness. You won't even be able to understand the question unless you've completed one particular environmental puzzle (in the mountain) and have found the entrance to the caves.
I am near 100% completion of The Witness, but I believe I may have accidentally blocked off access to an area of the game, specifically the end game area. I want to see if anyone else has had this problem or knows how to get out of it.
So first, I got this environmental puzzle: http://www.ign.com/wikis/the-witness/File%3ALevel3.png
Then, when I got to the bottom, I exited by going through the cave network, which means that the big stone door closed behind me.
Later, I was going back through the mountain to look for audio logs, and I realized that I enter the level with that environmental puzzle on the side of the blue path, which now goes nowhere. I can't make it exit the area, and I can't make it give me access to the other side.
So now it seems like I can't get past that level. Is that right? If so, it would be very unfortunate.