And it's happening on March 28th! I don't think even Barry is that fast. According to the article, it looks like Grant Gustin will be the only one from The Flash to appear in the crossover.
What I'm curious about is where Supergirl stands in the Arrowverse. Her existing on the same Earth as The Flash and Arrow is problematic because there's never been an acknowledgement of either Kara or Superman. You'd think that at some point in time, Superman would have been mentioned by somebody on Team Arrow or Flash. My theory is that Kara hails from an alternate Earth, like Jay and Zoom, and that Barry somehow ends up traveling there. Another question in the air is if Supergirl will reciprocate and show up on The Flash. I think a crossover with Arrow is a given, provided that the response to the first crossover is positive enough. Who knows, this all might eventually lead to a (at least) three-way crossover event, maybe even a four-way crossover if you throw in Legends of Tomorrow. If they could somehow wrangle Constantine into it, then hot diggity damn!
Yeah, I'm getting way ahead of myself.
Pictures via Hollywood Reporter and Fashion & Style.