Batman v Superman: Dawn of Justice* will establish the wider DC Universe on the big screen, and by the time the movie is over we'll have met Aquaman, The Flash, Cyborg, Lex Luthor and Doomsday**. But will there be other characters introduced? Will there be any easter eggs for the hardcore fans?
Yes! Lex Luthor has many agents making his dark agenda a reality, an agenda that includes keeping an eye on all metahumans, mainly a woman who walks the streets today but who is seen in pictures from the 1800s. A wonder woman, you might say. At any rate, one of Luthor's agents has a name, and that name is Anatoli Knyazev. Hardcore fans will recognize that as the name of the KGBeast, a Batman villain introduced in 1988's classic Ten Nights of the Beast storyline. In that story the Beast, an enhanced agent of the KGB, came to the US to kill ten targets, and he did it with extreme measures, including poisoning an entire 200 person dinner party to get one guy. He battled Batman to a standstill, and at one point when entangled in the Batrope the KGBeast cut off his own hand to escape. He of course put a cybernetic gun on the stump, as you do.
You won't see this version of KGBeast in the movie, but the character name is there - in the script at least - for those who care to pick up on these little easter eggs. One other easter egg: in the world of Batman v Superman the Joker already exists, and Superman knows about him. We don't see him in this movie, though.
* the real title
** By the way, let me confirm for you that Doomsday is in the film.