Board Thread:General Discussion/@comment-23917886-20170425113219/@comment-24152851-20170504055629

Flash is the only exception because his TV show was created before the DCEU Flash actor was cast. Also, the original deal was Grant Gustin would be playing Flash in the films too, before that got scrapped, so Grant was allowed to stay in his own TV show separate from the films.

The only reason they can do Gotham is because it's a "prequel" show. They would never be allowed to use a fully costumed adult Batman on TV with so many many consecutive Batman films lined up.

Lots of Arrow characters were killed off because they would be appearing in DCEU, like Deadshot and Amanda Waller, while guys like Captain Boomerang have never been heard of after his appearance in season 3.