Rocksteady Studios' Sefton Hill, the director on 2011's Batman: Arkham City, has confirmed that there are still "three or four" easter eggs remaining in the game that fans haven't yet uncovered. The revelation came during a panel at London's recent Kapow! Comic Con (via IGN).
"Some of them we put in there that were really obscure were found within a week [like the Scarecrow code]," Hill said. "We didn't think anyone would ever solve that, but it only took people two days. But there are still three or four things that people haven't seen - some of them very subtle things. There's one that we had right in one of the first demos that we did that nobody has found - it's in there if you look hard enough."
Rocksteady earned a reputation for burying fan-serving tidbits after Batman: Arkham Asylum's 2009 release. The game was filled with all sorts of nods to Batman lore, though the big one of course was the deeply buried reference to Rocksteady's Arkham City sequel plans in a carefully hidden secret room.
Multiple Batman: Arkham City easter eggs have already been discovered. In addition to the above-mentioned Scarecrow nod, sharp-eyed fans can spot things like Black Mask being beaten, Killer Croc in his cell, Calendar Man's reverence for important dates, and Harley Quinn's positive pregnancy test (sequel spoiler alert?).