Supergirl and The Flash got to have their crossover cake and eat it with Barry speeding over from The CW universe to CBS, even before Season 2 moved to the former. Many thought perhaps Kara’s Supergirl universe might end up folded into the “Arrow-verse” to facilitate easier crossovers, but producers now confirm the Girl of Steel will keep her separate Earth.

You’re warned of light Supergirl Season 2 spoilers from here on out, but Entertainment Weekly had a long conversation with producer Andrew Kreisberg over the changes from CBS to The CW, a brief snippet of which covered the question of merging universes. Supergirl will indeed make her way over to the Arrow-verse for the four-way crossover, but will inevitably return to her world:

Are you planning on bringing Supergirl into our universe?

Not for her entire world, but Kara will be traveling from her dimension to our dimension, “our” being the world that The Flash, Arrow, and Legends lives in.

It’s hard to fault writers for choosing to keep the two universes separate, as even if Barry’s “Flashpoint” or some aspect of the crossover managed to merge the two, a great deal more questions would arise. Does the Arrow-verse have a National City that Supergirl’s would somehow overwrite, and vice-versa for Starling and Central? Would aliens become a regular occurrence for Oliver and Barry, Superman included?

At the very least, word that the four-way crossover would involve DC’s Dominators could provide a clue to the two universes interacting. In the comics at least, the alien alliances that make up the “Dominators” includes a race known as the Daxamites, which just so happens to be the people of Mon-El, as played by Chris Wood in Supergirl Season 2.

We’ve seen our first scrap of footage from the crossover, but does it disappoint that Supergirl will stick to her own universe after the crossover? Will Barry’s speed always be required to meet, or will the series’ establish some other means of traveling back and forth?

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