4. A Post-Credits Big 3 Reference
I know Marvel did it first, but is there really a more effective, more non-disruptive way to create a larger movie continuity than by the simple inclusion of a post-credits scene? It worked tremendously well in the run up to the Avengers, and Im sure itd work equally well in the lead-up to the Justice League movie. Lets say weve seen at least one Wonder Woman reference and one Batman reference somewhere within Man of Steel; imagine a post credits scene in which the big 3, Superman, Batman and Wonder Woman, met to discuss the future of their chosen profession (possibly even at the invite of John Jones, a.k.a Martian Manhunter). Im not saying thats where the Justice League begins exactly, but the fact that these three are even meeting together together alludes to a future that we know will come to pass. Itd be a satisfying, fan-pleasing way to both foreshadow the upcoming super-ensemble piece, and also to solidify the germ of a connected DC universe.