Warning: This could be very fake!
UPDATE 1/10/14: This has been proven fake!
I have an iPhone video of the teaser trailer (it has updated since, but close with most things), and no, I will never distribute it, but I will offer this screen shot.
Again this could be a clever fake. But what the image shows is that Batman V Superman has been split into two movies with the first coming out on October 23rd this year and is titled “Enter the Knight” and the second part arriving on the normal March release date and retaining the “Dawn of Justice” title.
The only reason I’m even entertaining this is due to the rumored 10-month shoot for Batman V Superman, which led many people to believe they were filming Justice League back-to-back with it. Splitting the movie into two parts is a bit more believable than the Justice League rumor as that’s a popular thing for studios to do now (The Hunger Games, The Hobbit, etc.).
For a final time, this could be fake.