I'm not sure for this one. They're all a little different. Some of them have hidden things on the walls you can only see through the mirror for the other person.

[ jesus. robbie's really not looking so hot. or well, he is looking hot, but not in a healthy human sort of way. ]

Others have some kind of trick with the mirrors. Breaking them or something, but I've not been in one of those yet. I've only heard.