Ben Affleck's Batman has apparently been operating for well over a decade before his introduction in next year's Batman v Superman: Dawn of Justice, so it's obvious that he will have had many adventures before his first meeting the Man of Steel for the first time. There are numerous ways they could be acknowledged, but the Batcave seems like the most obvious place to provide the audience with a nod to at least a handful of them. The giant coin and T-Rex might be a little daft, but even a fleeting glimpse of a case containing Robin's costume would be amazing. When the young Jason Todd was beaten to death by The Joker with a crowbar, Bruce Wayne displayed his suit in the Batcave as a memorial, and its inclusion here would both pay tribute to that story and leave the door open for the Red Hood storyline to potentially be explored further down the line. A single version of Batman has never been around long enough to establish this kind of history in previous movies, and so an Easter Egg like this would at least flesh out the background of Affleck's Dark Knight, even if it is with something only comic book fans will notice. Then again, pretty much everyone should recognise Robin's iconic costume!
