If you order the book early, you'll get a Black Flash model to go with it. As for other minis, there's a Flash, Zoom, Green Arrow, Batgirl, Captain Boomerang, Hawkman, and Deadshot. There's special Batman and Joker dice, too. To help you know what's-what on the table, there's also a spray template and vehicle turning templates.
On the Marvel side of the equation there's Groot and the ragin' caijun, Gambit.
Source