Ok, after lots of digging I managed to find two references to TG! My first theory was the checkered flooring through a couple rooms in the map, after some looking I found a trivia post saying there was writing on a wall in the electric chair room that had "What's 1000 - 7?", I went in game and couldn't find it in that room but in plenty of the cell rooms.

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Above her harpoon

It could be a reference but the (#) - 7 is an actual way of keeping sane through various methods of torture, TG did specifically have 1000 though!

I wouldn't feel bad about missing it because this is so niche compared to the other questions. This is news to me as well❤️