Between all the slow-motion leaping and Beatles-covering, Billy Crudup rather surprisingly turned up in the most recent Justice League trailer as The Flash's father, Dr. Heny Allen.

Which has sent comics fans wild on the revelation that Dr. Henry Allen is currently serving jail time in the DCEU; an indication that the films may be following in line with CW's television series The Flash and introducing his archenemy, Reverse-Flash.

Though there's no indication in the trailer as to why Barry Allen (Ezra Miller)'s father would be behind bars, he's falsely convicted in the comics of murdering his wife (and Barry's mother) Nora Allen.

In fact, Nora's real murder is Reverse-Flash, otherwise known as Professor Zoom, or Eobard Thawne; an individual who possesses similar powers to The Flash, and who travels back in time to kill his mother and frame his father.

Don't expect Reverse-Flash to make any kind of appearance in Justice League, however, since the film's already looking crowded enough; having to introduce The Flash, Cyborg, and Aquaman to the DCEU and the superhero team established by Batman and Wonder Woman.

Justice League - Comic-Con Trailer

If Dr. Henry Allen's imprisonment does really hint a future appearance by Reverse-Flash, Justice League is likely establishing the necessary set-up for The Flash solo film, which could see Eobard take centre stage as the film's main villain.