They've spent the last few months filming Joker beating the shit out of Gotham. I know there's the robbery, him crashing a party, the evacuation, and all the chase scenes with the Jokermobile.
That's what's been DONE. There's still like 100 days or more of shooting.
Scarecrow's role is smaller in this one, but all of his scenes are supposed to be integral or something.
The general consensus is that Two-Face appears in the end and has a couple of scenes (one or two). The descriptions I've read are exciting (blood and boils!)