Plot hole: Several: 1. How did Hush get Batman's fingerprints on the knife? 2. How can the likes of Mad Hatter, Zsasz, and Deadshot go through the prison city without being spotted? 3. Why wouldn't Batman suspect Ra's al Ghul of being the power behind Strange once he discovered him in the prison city?
Mr. Freeze: You will bring me Nora or you will die.
Trivia: When doing the side-mission "Enigma Conundrum", after going to where the first Riddler room is located, look up and you will see a sign for a place called "The Black Canary." The Black Canary is another DC Superhero and member of The Justice League.
Answer: Listen to the fourth Riddler interview tape. He did a psychological profile of Batman, then picked among candidates as to who could be Batman. He's also smart enough to realize only a rich man could afford all of Batman's gear and vehicles.
Rob245