In the cafeteria, there is a painting of the cafeteria room in its exact state (which includes the decaying walls, the dead body of a man lying against the table, and the same painting located at the back of the room). The fact that such a painting exists doesn’t make any logical sense.
It is possible that the prison was used as a sort of execution site. The gallows in the prison would have been used to hang the prisoners and their bodies would then be thrown into the small hole that James eventually jumps through. The room that James jumps through also has a staircase, allowing the executioners at the prison to take the bodies and put them into the nearby morgue. The bodies in the morgue would then be thrown into another hole, as James states, “This corpse… into this hole?”.
On the gallows, we can see 3 ropes. Maybe one for James, Angela and Eddie.
The 3 tablets use for the gallows puzzle may represent James, Angela and Eddie.