6. A Nod To The Wider Comic Mythos
One of the coolest moments in Arkham City was the sudden realisation that this version of Batman had a Robin - and he was on-hand to help out whenever Bruce needed him. Now that might not seem like much, but it's in how sudden his reveal was that made it so awesome - not to mention the fact comic fans love a good cameo every now and then. Things like wandering through Arkham Asylum and seeing guys like Calendar Man or references to Harvey Dent's time there were both great little nods too, and it serves Rocksteady's all-encompassing master plan that they'd already be planning a number of potential threads to later pull at somewhere down the line. Whether it be a mention of Miranda Tate alluding to the eventual birth of Damien Wayne, a torn Joker mask looking like someone is about to ape the Scott Snyder rebooted version or anything in between, the whole 'shared universe' thing is 'in' right now, and Rocksteady have everything at their disposal to capitalise on it.