Watch video below featuring Batman Vs. Superman producer Deborah Snyder talking about a Star Wars Easter Egg that was included in the movie as well as a Henry Cavill cut scene.
Both Batman Vs. Superman and Star Wars: The Force Awakens filmed at the same time. Zack Snyder happens to be a big fan of Star Wars (and was at one time rumored for a SW movie). Snyder released an image of a Jedi Superman Henry Cavill (above), which saw Abrams follow suit with images of his own, only for Snyder to do so as well (see below).
Deborah Snyder actually reveals they created a special Batman Vs. Superman Star Wars-themed trailer, which was for their personal use, but hints it may be released at some point.
The Batman Vs. Superman Star Wars Easter Egg is of Lex Luthor as prisoner TK-421, which is the name of the Stormtrooper from Star Wars: Episode IV that Luke and Han stole the stormtrooper suit from used to infiltrate the Death Star.
Regarding the Batman Vs. Superman cut scene, it involved Henry Cavill as Clark Kent investigating Batman in Gotham City.
Watch Deborah Snyder talk Batman Vs. Superman below.