The Flash won't be the only Justice Leaguer to appear in his 2018 movie, as Cyborg will be featured as well, according to Variety. The part, played by Ray Fisher, first appeared in this year's Batman v Superman: Dawn of Justice, and will be seen in next year's Justice League.
The Hollywood trade says that the exact size of Fisher's role in The Flash is unknown, but says that his appearance is "another signal" in DC Films' goal to have a interconnected universe - and for Cyborg's part, to build to his planned 2020 solo film.
The Flash had a surprise cameo in the recent Suicide Squad, with his appearance there only leaking out weeks before the film's release.
Director Rick Famuyiwa is scheduled to begin shooting The Flash later this year in London, aiming for a March 16, 2018 theatrical release.