As (again needlessly) revealed in the trailers, the sequence that sees Batman preparing to fight Superman and stab him with the Kryptonite spear has a Riddler question mark in the background. Could it be an acknowledgement of the fact that The Riddler was initially intended to be included in the film? There's also a tag that reads Joe + Kayla, which some are taking to be a reference to Joe Chill or the Joker, and the bottom of the pillar beneath the Riddler question mark reads Aphrodite - who was of course the creator of the Amazons, and thus Wonder Woman. There is some suggestion that there's a Watchmen reference in a tag elsewhere in the film, but it's a difficult one to spot. It would however perfectly suit the premise of the movie, which basically recycles Snyder's first DC movie plot.