Board Thread:Arrow discussions/@comment-807326-20171020051525/@comment-1410838-20171020160447

Diagonally33 wrote: On Supergirl's world there is Gotham.

Supergirl s01e01 'The Adventures of Supergirl'

Father saying to his family: "We're moving back to Gotham".

 Central City and Star Labs exist on Earth-38, as seen in World's Finest, so it's not a stretch to think Gotham City exists on different Earths, too.