First off, we've got the newly moved Arkham. Note that this time, it's on the outside, as you can read the lettering, there's a cop car outside, and a Wrong Way / No Thru Street sign.
As things pan back, it reveals that Arkham's now in a more downtown location. This makes it seem like you'll be crawling through the city, and dragging the various scum from Gotham back to jail.
As it moves in to the various crimes going on, there's "Long Live Joker" tagged onto one of the buildings where all the other Clown Thugs are.
Possible Villain Clue: The Iceberg Lounge. Owned by Penguin. A little hint that he could be appearing in the game.
Possible Villain Clue: "We Want You" poster featuring Two-Face.
(more clear version from the website). Showing the two-tone clothes, although the face is mostly obscured, you can see his chin is a burned red on the left half.
As we can see, Harley is back, and tending for her man. God only knows how she got out, or if she's gonna pose a real threat this time around. Though I didn't show any images, they're in an abandoned Amusement Park (with a possible dead guy in a bumper car).
Aaaaand the Clown Prince of Anarchy himself. Face still messed up from his Titan injection at the end of the first game, and he's hooked up to some blood from Gotham General (in an IV in his left arm just below screen).