The topsy-turvy crossover began with Dr. John Deegan manipulating reality and switching Oliver Queen and Barry Allen's identities. The second chapter ended with him stripping the duo of their powers and reimagining them as a notorious pair of criminals called the Trigger Twins. To make matters worse, a black-suited Superman arrived on the scene, looking extremely not happy.
With the fate of reality hanging in the balance, it's heroes versus the Monitor, Deegan, and a twisted version of Superman in a showdown of epic proportions.
"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." Melissa Benoist told SYFY WIRE and other members of the press on the Supergirl set in Vancouver. "And 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."
The writers littered the event with Easter eggs and the introduction of iconic characters, including Daily Planet reporter and Superman's lady love, Lois Lane.
"Kara's known Lois for a while in our story, in our universe," Benoist said. "But playing scenes with her for the first time, the way they've written her is perfect. I think people and fans, especially of that mythology, will really love it. And Bitsie Tulloch just nailed it."
Another nostalgic nod centered on Kara, Clark, Lois, Oliver, and Barry coming together on the Smallville farm.
"That was really, really exciting," Benoist says. "All of us were besides ourselves. To pay tribute to that show felt good. When you're there, even though it's in Canada, it feels like pure Americana. It's kind of weird. There are some really, really lovely, heartwarming scenes on the Kent farm."
So far, Batman has been notably absent from the Arrowverse. Even the long-running Smallville TV show stayed clear from Gotham City and the Dark Knight. However, last night's Arrow saw the debut of Batwoman, a prominent character in the Batman comic books and her own adventures.
"Ruby Rose just killed it," Benoist says. "She killed it. She is so perfect for this role. I've been around Caity Lotz and she's a badass... but it felt so good to have another female presence there amongst the boys. Their scenes are really nice because of their similarities. Kate Kane is Bruce Wayne's cousin and all these things, so they really relate on a lot of levels that I don't think Kara's found yet in another female superhero. There's a really deep understanding from the get-go between the two of them."
As for the highly-anticipated climactic confrontation between Supergirl and the Elseworld's darker Superman, Benoist would only offer the smallest tease: "You can expect some really dynamic fight scenes."