‘Justice League’ and DC’s TV Shows Are Taking the Multiverse Approach
In case you couldn't already tell by the way things are playing out between all the DC properties, there's no real continuity like there is with the Marvel films and television shows. Where Marvel has a vision and a plan in place with everyone working together in harmony to realize that vision, DC is like a room full of introverts with their heads down, doing their own thing. Marvel has the Cinematic Universe which has now extended to TV, and to explain what DC is up to, Chief Creative Officer Geoff Johns is likening their approach to a concept DC comics fans will instantly recognize: The Multiverse.
In the DC comics universe, there have existed multiple universes, or The Multiverse, a concept first introduced in 1961 with the addition of a second Earth. More parallel universes followed, allowing for infinite versions of characters and worlds and ways for authors to explain away clashes with continuity. This is also a really great way for someone like Geoff Johns to explain DC's approach to movies and TV, if he were so inclined.
And he was, in an interview with BuzzFeed. Johns explained that while yes, 'Arrow' and 'The Flash' exist in the same universe, their movies and TV properties don't ... on purpose:
We look at it as the multiverse. We have our TV universe and our film universe, but they all co-exist. For us, creatively, it’s about allowing everyone to make the best possible product, to tell the best story, to do the best world.
Everyone has a vision and you really want to let the visions shine through. I think the characters are iconic enough. I like [Marvel’s Agents of] S.H.I.E.L.D. a lot. I love what Marvel does. I’m a huge fan. It’s just a different approach … You have to have conversations about what’s happening in TV and film between everybody because you don’t want to do the same thing.
You could read into his use of the word "multiverse" as a hint that perhaps we could see crossovers between 'Justice League' and DC's TV shows, with even multiple versions of the same character teaming up, but it seems like DC is content with the way things are. Johns has kind words about Marvel, and does admit that they've considered the possibility of a TV spinoff similar to 'Agents of S.H.I.E.L.D.' somewhere down the line, though:
There’s been discussions over the years for both, obviously. You never say never. Maybe one day we’ll link a show to a film if it makes sense, but the creative process we’re going through right now is to let the stuff live and breathe and be its own thing and own it.
The Multiverse was always a way for DC to explain discrepancies in continuity, which is exactly what Johns is pretty much doing right now. Marvel has the Cinematic Universe, DC has The Multiverse Approach aka "Ehhhh."