Understandably, given the heritage of the film in terms of its own franchise, as well as the fact that it is a comic book movie, X-Men: Days Of Future Past is full of Easter Eggs, references and in-jokes aimed squarely at comic book fans. It's almost a cliche now to say that the genre is as fundamentally defined by these fan-baiting references as it is by any over-riding film-making tropes. Writer/producer Simon Kinberg spoke recently about the desire on the project to appeal to fans of the film series, and engage them in a way that paid due homage to the films that came before:
"We wrote it wanting it to be a really deep dive for the fans, so that almost every scene would have little tickles of other moments from the comics, or moments from the movies. But we also wrote it with the intention that its going to be the most watched X-Men movie of all-time, and if it works, its going to bring an audience thats never seen these movies, or only casually seen them. So those things need to be invisible for a general audience.With that in mind, it's no surprise that the film is packed with references that are among the most obscure in comic book movies, though it's not quite true that the film's call-backs and references acknowledge all of the X-Men movies to date.