I have to wonder if we're being mislead with the trailer, and if Riddler turning himself in is something that happens much earlier than the film's plot would suggest? We're assuming this is a big, John Doe reveal, but that would be a really big plot point to spoil in the trailer for the movie. So what if this is something that happens before Batman is even on the scene? What if the Riddler, before going on his killing spree, and interacting with Batman, was caught by the cops a year or two before, and simply put back on the street, without the cops have any idea who this guy really was?
What makes me think this is the fact we see the slow closeup of the cup with the question mark. It acts as a reveal for the audience more than a relevant plot development for the characters, because presumably the audience would know this was the Riddler who was being arrested. So it feels more like ominous foreshadowing, to me.
Another thing, when Riddler is being pulled out of the diner, you hear a cop yell "Get outta here!". That's an odd thing to say to what we're being led to believe is a wanted man. That's more the type of line a cop would yell at someone who was in the way. We're assuming there's some manhunt for him, and this scene is the culmination, but maybe this was a completely separate incident?
We also assume that the Riddler is talking to Batman in the prison scene, but the trailers have been cagey regarding Paul Dano's appearance. Iwonder if we're actually even seeing him behind the screen, and they're simply making it seem like he is for the trailer?