Trivia: When the painting in Lex's office is turned upside down and the demons are descending from the sky, they bear a striking resemblance to Darkseid's Parademons. A possible/likely foreshadowing for the Justice League movie.
Trivia: In the film General Zod's home is identified as being Kandor, a city on Krypton that was eventually stolen by Brainiac, shrunk, and hidden in a bottle for observation. In the comics, both Zod and Jax-Ur (who was referenced in Man of Steel) lived in Kandor at some point.
Trivia: The lightning tornado dream sequence echo voice thing is the DC Extended Universe version of The Flash, The Flash appearing in mysterious form, kind of like a dream, and possibly from a different point in time, is very much a reference to Crisis on Infinite Earths where Flash was appearing to various heroes trying to warn them of what was to come while he was busy dying later in the story fighting the very same threat.
Trivia: Batman's regular and armoured suits in the film are very close in design to those from Frank Miller's The Dark Knight Returns.
Trivia: S.T.A.R. Labs is a research facility originated in Superman #246 some 45 years ago, and currently a key component of CW's The Flash TV series. The lab was also the employer of Silas Stone in Teen Titans - and it's Silas who we see creating Cyborg at the lab in that truly spine-tingling video recording on Diana's laptop.
Trivia: When Batman is at Gotham Docks, lying in wait at the wheel of the Batmobile as the Kryptonite is unloaded, the warehouse he is hidden in bears the name Nicholson Trading Co., a reference to Jack Nicholson's legendary take on the Joker in Batman.
Trivia: The spaceship held by Superman has the number 003 as a reference to 300, another Zack Snyder film.
Chosen answer: The beginning is Bruce Wayne's perspective of the events that occurred in the movie "Man of Steel" when Superman and General Zod are fighting (if you haven't seen it, it would explain a lot of BvS events). It's General Zod's ship and the phantom drive. It cuts to 18 months later. Supermen is called to testify in front of a congressional hearing because of his vigilantism over the past 18 months and people are concerned about his actions (like the events in Africa) since he's an all-powerful alien with no way for the people to stop him, so they're very nervous. Bruce seems to blame Superman more than anyone though for the destruction and death of people he knew (and tried to save) because if Superman wasn't on Earth, Zod wouldn't have come to Earth, etc.
Bishop73