Did you know in Arkham Asylum if you go into Warden Sharp's office and blow out the left wall you find a secret room with the plans for Arkham City on the right wall?
Also, if you run a pirated copy of Arkahm Asylum, your glide animation is really glitchy and doesn't work most of the time. One user posted a complaint about this on the official forums, to which the developers promptly told him that it was because he was running a pirated copy of the game.
Not sure if this has already been posted, or if it even counts, but it was funny