Batman V Superman: Dawn of Justice already has the Trinity, Aquaman, and Cyborg in appearances and now there is another member of the Justice League confirmed.
Batman News.com found this bit of information from Comic Con Brazil regarding another member of the League who will show up in the movie:
“Well, Iâ€™m not really at the liberty to talk about The Flash right now, but itâ€™s something that youâ€™ll be seeing in the future in our films. You do get a glimpse of him, of course, in Batman v Superman. But Iâ€™m really looking forward to taking the amazing, iconic costume for The Flash and interpreting it in a fresh way where Ezra Miller is playing The Flash. Heâ€™s an extraordinary performer, he has a sort of interesting sense of humor and the youth that will be great for Barry Allen and I think heâ€™s going to make a great Flash.”
So that means only Green Lantern and Shazam aren’t currently rumored to appear in the movie. It’s doubtful they would be, as the current rumor is that Green Lantern will make his debut in the first Justice League movie.