While fighting Prototype LexBot near the end of level 9, the robot runs into the walls and can be hurt similar to Bane and the Titan Thugs from Batman: Arkham Asylum.
Batman: Arkham City
During the intron for level 4, "Arkham Assignment", Vicki Vale refers to a failure to have the inmates locked up in a walled off area of Gotham City by the mayor. This is a reference to what occurs in Arkham City. Additionally, listen when Vicki Vale says "Hey, at least the mayor's plan to let them loose in some vast, walled off area in the heart of the city got put on hold. Now, that would've never have ended well" in the news report.
Superman theme music
While flying as Superman outside of a level, the theme from the Superman movie will play.
Activate the following cheats by entering the corresponding codes at the main console in the Batcave. Note: These codes only make the items available for purchase. You'll still need enough studs to buy them:
The Red Brick Minikit finder costs 50,000 studs to buy. In Gotham Park near the park, play the mini game with the boats. Shoots the subs with your boat.
The Red Brick X2 is found by locating the Remote Bat Computer near the police station. Turn left and you will see a mini-game. Play the game and smash the cars with your hammer car to receive the red brick x2.