Jonah Hill passed on it because he was asking for $10 million and he didn't wanted to play Penguin, he wanted The Riddler role. WB wanted to keep the budget down for this film and its going to end up being the right decision. To be honest, they make get a lot of that money back on merchandise alone lol
I'm happy he got to see it early because the press release or whatever for the movie will not have his name on it. I guess he didn't contribute enough to get credit on it.