Based on DC's Flashpoint comic, The Flash will follow Barry Allen when he inadvertently changes his universe following his journey back in time, and this film is rumored to bring massive changes to the DC Extended Universe.
7. Batman Will Die
6. Flash Creates the "Burtonverse"
5. Barry Will Create the New Flash
4. Zod Will Rule Over the New Earth
3. Val-Zod Will Appear
General Zod's return could herald the appearance of this fan-favorite hero, as there have been reports of this character being adapted for live-action by Warner Bros. For those of you who don't know, Val-Zod is a Kryptonian orphan who takes up the mantle of Superman in his own, alternate universe. While his parents were never revealed in the comics, his name suggests that he is the son of General Zod, and this film might make it that way with the return of the alien warlord.
If the evil Kryptonian does take over this new Earth, Val could help the Flash and his allies rise up against him, making for an interesting battle between father and son (especially since the Flash's relationship with his father is an important part of his character). It could also allow both Val and Supergirl to fill in Clark Kent's place as their world's Superman.