The rumors that The Flash is going to start production in 2019 appear to be true.
Geeks WorldWide, which is a reliable source for movie production info, is reporting that The Flash will film at Warner Bros. Studios in Leavesden, UK. This studio will be no stranger to The Flash star Ezra Miller. He’s filmed Justice League there, as well as two Fantastic Beasts movies. The studio was also home to Wonder Woman and is currently being used for Wonder Woman 1984.
Earlier this summer, The Flash co-director John Francis Daley hinted that if all goes well, The Flash will be released in 2020. That would mean it’d have to start shooting by 2019, and it seems like it’s on track to do so.
SOURCE: Geeks WorldWide