Zack Snyder tweeted a pic of himself and Jason Momoa (Aquaman) what's really interesting in the pic is the costumes in the pic. The obvious ones are Aquaman's and the Flash on the left but there are a number of other ones, some major question marks.
On the left side is a black costume people have made comments to it being Nightwing or Green Lantern but there is a possibility it could be an updated Bat suit closer to Christian Bale's suits. There is a pic that appears to be Mera behind Aquaman also there is a mannequin that is covered on that side.
On the right side there is a Bat cowl but there is another costume face away from the camera it appears to have gloves of some type and shoulder armor. On the table in the back there is an odd looking boot with flaps on the sides there also is a helmet that look somewhat like Dr. Fates helmet.
Well that a lot of hints to wet our appetites more as we get official info.