3. The Crime Of The Century
Since this is a game about origins, and following on from the Flying Graysons' poster in the background of the game, there's also an important, and slightly heart-wrenching Easter Egg in Crime Alley that heavily references the most important moment in Bruce Wayne's young life. In Arkham City there was an Achievement called Pay Your Respects, which charged the player with heading to Crime Alley and interacting with the crime scene of the Wayne family murder, where a bunch of flowers marked the tragic spot, still with chalk outlines of the bodies. Arkham Origins follows the same thread, including the same chalk outlines and indeed the same single red flower in Crime Alley from the earlier game that of course comes later in the series. It's a no-brainer to have the detail there, but that doesn't make it any less good to see that it was.