The teaser trailer for Batman v Superman: Dawn of Justice that was shown at Comic-con last night just leaked online, see it here.
Last night at Comic-con in San Diego, director Zack Snyder revealed the first photo of Gal Gadot as Wonder Woman and not only that, attendees at Warner Bros panel were so lucky that they got the first look at Batman v Superman: Dawn of Justice when the teaser trailer was previewed to them. That's right Warner Bros has already a teaser trailer for the film and it was shown at Comic-con but has not released online yet. However someone from the panel, an attendee, managed to record the clip and uploaded it online for many fans to see.
On a post on ComingSoon.net by Silas Lesnink that talks about the teaser he described the teaser trailer clip with the following words...
"Batman is standing on a Gotham rooftop in the rain. His costume isn't what we've seen already. It's big and bulky, like his armor in The Dark Knight Returns. His eyes light up, solid white. He's moving a tarp, revealing the bat signal He turns it on and the camera tracks up to the sky. Superman is there, hovering in the light, and he doesn't look happy. His eyes light up with heat vision as he glares at Batman."
Then not long after that, I found a post from CinemaBlend that talks about the trailer plus provided a link to a video uploaded online which shows the recorded clip of the teaser from the Warner Bros panel. You may go ahead and watch the teaser clip here, it's not clear though and looks like a smartphone was used to record this but the video is still recognizable. If it's still online you will be lucky to get to see it as Warner Bros may request to delete it as soon as they find it out or they may just officially release it online which is going to be awesome.