The hour also marked the 'Arrow'-verse introduction of Lois Lane (Bitsie Tulloch).


[This story contains spoilers from part one of The CW's DC crossover "Elseworlds."]


When The Flash, Arrow and Supergirl crossed over Sunday for the first part of the highly-touted “Elseworlds” arc, The CW dramas paid homage to an unexpected series: Smallville.


During The Flash hour of the event, Barry (Grant Gustin) and Arrow’s Oliver (Stephen Amell) woke up to discover they were trapped in one another's lives. But while the issue persisted on Earth-1, they realized Supergirl’s Kara (Melissa Benoist), who lives on Earth-38, might be immune from whatever was going on.


Cut to Remy Zero's "Save Me," the theme song from The WB Network-turned-CW's DC Comics predecessor Smallville theme song, as the superheroes traveled to the other Earth and found themselves on on the Kent farm. (This marked the first time the Arrow-verse used the Kent farm; production on The Flash also used the same location that Smallville used.)





Smallville, which followed a young Clark Kent (Tom Welling) as he evolved from a teen with abilities to the eventual Superman, ran for 10 seasons on the former The WB before the network became The CW. A number of current behind-the-scenes talent from the Arrow universe — including Batwoman writer Caroline Dries — previously worked on Smallville; Erica Durance (who portrayed Lois Lane on the series) is a legacy casting and recurs on Supergirl as Alura Zor-El .


"Just the whole idea of going to the farm and the homage to Smallville … that was an idea that came up pretty quickly,” The Flash executive producer Todd Helbing told reporters during a screening of the episode. He credited episode writer and former Arrow showrunner Marc Guggenheim with putting the theme song shout-out into the script.Story-wise, Supergirl executive producer Robert Rovner felt the Kent farm was a good place to reset the characters after Kara (as Supergirl) refused to reveal her identity to the president in the previous episode. Plus, “Clark has been on Argo City, so it felt like a great place for them to reconvene and figure out their problems together,” he said.


It also allowed the Arrow-verse introduction of Lois Lane (Bitsie Tulloch). “It was amazing to have Clark and Lois together on our show,” Rovner said. “We’ve dreamed of having Lois Lane be on Supergirl; we’ve talked about her since the beginning. When I first saw them together, it felt like we were entering the canon in a new fresh way — seeing them reunite for the first time in our universe, that was thrilling.”