I think it is Harley but I think she is just being held by ARGUS and won't be really seen outside of maybe Diggle walking past her cell. That alone leaves the viewers to believe that there is a Harley therefore there is a Joker and Batman already running around in this universe. They have already stated that Man of Steel's Batman will be older and have been being Batman for awhile before the events of Man of Steel. Which means Arrow and Flash take place leading up to the events of Man of Steel. Batman and his rogues have already been going at it therefore Harley being imprisoned by ARGUS in Arrow. I can dream. Have this season of Arrow end with Diggle, Roy, Ollie, Barry, Sarah and Felicity in the lair and the lights going out and the monitors flashing to... Chills The events of Man of Steel taking place between Season 2 and 3 of Arrow. Season 3 of Arrow could be Ollie and Starling City adjusting to this new world and its implications. This would allow for Ollie to perhaps show up in at least a cameo role in Superman/Batman or perhaps get a mention.