Thanks to Collider who translated the basics from the Omelete article (it was in Portuguese) after they received an onset visit to the Dark Knight sets.
The details are listed out here;
• Gotham City will go through a “white night”
• for the first time in the cinemas, Batman is going out of Gotham City, ie, Hong Kong
• Two Face will be in the film
• And the most important information they got… there will be a 6 or 7 min prologue about the Joker that will be show before “I Am Legend” in IMAX cinemas only.
First of all, the theory behind the scene they will show is that it will be the bank robbery scene where the Joker gets his smile which, in this take, will be a scar.
Two Face will likely only play a small part if I’m any judge, and will pop up towards the very end of the movie as a link to the third Batman movie. As for the white night, I did a bit of searching, and found out that a white night is essentially a night with no darkness.
Because the sun is at the horizon to 6 degrees below the horizon, locations above 60 degrees latitude that are south of the Arctic Circle or north of the Antarctic Circle experience a white night, or a civil twilight. St. Petersburg is famous for them, with poetic almost stylistic walks along the city’s rivers and canals at any time of the day or night, in almost broad daylight. They occur in St. Petersburg around June 11 to July 11.
How this will be a feature of the film is, in my opinion, relatively obvious, when you consider the alternative in the Simpons when Mr. Burns blocked out the sun. No doubt, it will be a part of the Joker’s plot against Gotham. But who knows.