Look what I found! I don't know if others have found it also, but in the ruins, there's a boarded up door on the right. Press and hold the floor to make your character sink into the ground and walk under it. This room is behind the fallen file cabinet in the next room.
There's a conveyer belt with fire at one end and a conveyer belt to a roller/crusher on the right.
Nice find! Seems like Bluesnow is putting in at least one easter egg each game.
Not to be picky, but that is a boarded-up doorway (no door in frame) to access the torture chamber, and not a boarded-up door. Trying to go under the boarded-up doors puts you outside the game.