I didn't realize this until afterwards but something didn't make sense.
Them releasing that prisoner but really just transferring him makes no sense at all. Of course he's going to tell everyone that he was supposed to be released and served his time and yet was sent back to prison and of course that would cause a problem where they have to kill everyone. Just kill him outright or drum up fake charges to keep him there without "releasing" him. All it did was literally create a problem that didn't need to be created. Great episode though.
They said that he was supposed to be sent to Level 4, but accidentally went to 2. My take on that was that 4 was where they always sent "released" prisoners, so it wouldn't matter if they talked.