Man of Steel was not loved by everyone, to say the least. People did not want to accept that Superman would cause such devastation, and since they were used to Marvel films they were expecting the movie to follow more of a lighter tone. However, it was very comic accurate, and many diehard comic book fans approved of it.
It had many nods towards Bruce Wayne, as well as Lex Luther, which we now understand the reason for, of course.
However, after recently watching it again, I discovered something that I had missed before. If you don't want spoilers I would stop reading now.
Remember that end scene, where Superman drops a satellite near General Swanwick? After he left, the officer with him called Superman 'hot.' It provided a little humor at the end of the film, and most comic books fans thought it was just that. However, Zack Snyder brilliantly placed that in there.
This officer is none other then Carrie Farris. This directly ties the Green Lantern to the DC Cinematic Universe. Carrie Farris plays Green Lantern's love interest in the comics.
So, I know it is not a big deal now, since we know the Green Lantern will receive his own movie in the future, but this cameo was intricately placed in the movie, to reference how Zack wanted to grow the universe. If Hal somehow makes his way into Batman vs Superman, he could interact with Carrie since she is also confirmed for BvS, as well as Justice League.
Christina Wren is set for a return in Justice League.