Supergirl's Kara Zor-El has a special role in "Elseworlds," this year's three-show Arrowverse crossover. When Barry and Oliver go to her for help, she'll recognize them both for what they really are.

"What I liked the most about this year's crossover, I think, more than any other crossover that we've done so far -- aside from the musical episode, which was my favorite; I had so much fun doing that one -- but this one was so fun in particular because it really was the triad, so to speak, the three of us," Supergirl actor Melissa Benoist shared during a set visit. "Kara plays a really fun role in this dilemma that Barry and Oliver find themselves in. She's the only one that really recognizes them for who they are in this Freaky Friday situation, and it's really comedic. The whole thing. I think people will really get a kick out of it."

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As Benoist mentions above, Oliver Queen and Barry Allen have swapped lives in the crossover. Thanks to Arkham Asylum doctor John Deegan, who was granted the power to rewrite reality by crossover villain The Monitor, Oliver is the Flash and Barry is the Green Arrow, and their respective teams are completely unaware of the switch.

However, it looks like Supergirl -- who hails from another universe entirely -- won't be subject to this massive change. Per Benoist's comments, she will recognize Barry and Oliver from their team ups before Deegan's dabbling. This will likely come as a massive relief to the two Earth-1 heroes, whose own teams don't believe them. Their timing also couldn't be any better, since The Monitor is a multiverse-wide threat that's sure to encroach on Supergirl's Earth sooner rather than later.

This year's Arrowverse crossover event will involve the casts of Supergirl, Arrow and The Flash. The event will unfold over three nights, starting with a special episode of The Flash on Sunday December 9 at 8 pm ET/PT. Then, it continues Monday, December 10, with Arrow, and concludes on Tuesday, December 11, with Supergirl.