Superman Batman film I Am Legend
I am Legend is a Warner Bros movie. There are multiple easter-eggs in the movie pointing to "future" WB movies. You have that Superman/Batman sign (the Superman logo in that one is the one used in Superman Returns with Brandon Roth), there's also a Green Lantern movie poster in the video store as well as a Teen Titans movie poster.
WB owns DC comics so them putting in those little bits was a mix of fun and a way to get fans talking at a time when all of those projects were in development. Superman/Batman was ultimately scrapped due to the critical failure of Superman Returns, Green Lantern happened and I don't know the fate of the Teen Titans movie.