Arkham City remaining Easter eggs
Right now, I'm playing Batman; Arkham City and I'm close to a platinum trophy.
But besides getting all trophies, I'm a fan of eastereggs and hidden references,
and I was just reminded of an interview with the producers of Arkham City, where they mentioned that 4-5 eastereggs still haven't been found.
So, my question is, if there are any hardcore Bat-fans or AC-players here;
Are there any references or eastereggs you found in the game, that haven't been mentioned on the internet yet?
If so, where and when in the game did you find it?
EDIT: The one I found myself, allthough I'm not sure if it's a known easteregg, but the pianotunes you hear on the radio (Also on the radio where you hear Jack Ryder in Arkham Asylum)
are the same tunes from the Batman Forever game on the SEGA Genesis.