We’ve recently been drawn to this impressive post at the SuperHeroHype forums by ChicageauxTiger:
This was the general scene of the shoot:


Continue reading for the spoilers.
It turns out that a number of the big-wig movie characters were there, in force. First up, we have Aaron Eckhart — or Harvey Dent:

Second is Anthony Michael Hall:

Gary Oldman:

…and, rather importantly, Heath Ledger — not donned up in full Joker details, but still sporting a scar:
