The Internet is a powerful tool. It can spread information incredibly fast, and sometimes that information is slightly compromising for some group. In this case, that group is the production team of [Batman v Superman: Dawn of Justice](movie:711870). A Reddit user posted some photos from set (which have since been removed, however the damage is done), and after some speculation, these could turn out to be big.
One of the photos appears to be taken from the scene where we see Thomas and Martha Wayne's graves. In the picture, it appears that there's the grave of Dick Grayson (also known as Robin).
Previously, there were rumors that a dead Robin would appear in the film, in a glass case in the Batcave. It looked like there might have been a quick glimpse of Robin in a suit in the background of a shot in the trailer. However, given the history of the comics, lots of people speculated that the dead Robin would be Jason Todd. It's rumored that Robin has moved on from his past identity, and has "graduated" to become Nightwing.
Some talking heads on the Internet seem to think that it could possibly be John Grayson, the father of Dick. It would be strange (but interesting) if John Grayson's body was buried on what appears to be a family plot on the grounds of Wayne Manor, though.
Dick Grayson was supposed to die in the 2005 comic book insane mega-event "Infinite Crisis." The plot decision was made at the last minute, partly because fans heard about it and were not happy. Recently, in last year's event series "Forever Evil," Dick's heart momentarily stopped - he was then resuscitated in secret and taken away to work as a spy for an organization - leaving his identity as a superhero in the past.
A "false" or "fake" death could play into the DC Cinematic Universe, and it would give Amanda Waller and the Suicide Squad team a foil in Batman's first sidekick or it could allow the filmmakers to bring him back at any given time even though his death was established.
There's also a rumor that they put Grayson's grave on set just to throw people off or for fun - however, it doesn't seem to be something the production team wanted on the Internet very long, which leads me to believe that it's not just a gag or a joke. They requested people to take down the images ASAP once they had found out that they'd leaked on Reddit. Obviously, we would have included the photos if we had them. Alas...
Here's the link to the new trailer for [Batman v Superman: Dawn of Justice](movie:711870). It looks sweet.