'Supergirl' 'Flash' & 'Arrow' EPs Dish on 'Smallville' Easter Eggs in 'Elseworlds' Crossover

elseworlds crossover smallville farm
Katie Yu/The CW

Fans of The WB's Superman series, which ran from 2001-11, were in for a treat on Sunday's special crossover episode of 'The Flash.'

The CW's Elseworlds crossover kicked off with a special episode of The Flash on Sunday, and featured a pretty epic moment for longtime fans of DC Comics' various TV adaptations. 

The crossover event -- which this year includes Arrow, The Flash and Supergirl -- opened with Oliver Queen (Stephen Amell) and Barry Allen (Grant Gustin) realizing that they've swapped bodies and the whole world believes them to be living the other's life. When the guys ventured to Earth-38 to see if another of their super-powered pals, Kara Danvers, aka Supergirl (Melissa Benoist), remembered them as their true selves, they landed in a very familiar spot.

As the familiar strains of Remy Zero's "Save Me" swept nostalgic fans back to the early aughts of The WB, Barry and Oliver touched down on the Kent farm -- the same Vancouver location used for young Superman's family home on the Tom Welling-starring series, Smallville, which aired on the network from 2001-11.

"Just the whole idea of going there and going to the farm and the homage to Smallville, yeah, that was an idea that came up pretty quickly." Flash showrunner Todd Helbing told reporters last week of the fun Elseworlds nods to DC TV heroes past. "It was probably at the same time that the song came up."

While Helbing and his fellow crossover producers couldn't recall exactly how the ideas for the tribute came about, they credited former Arrow and Legends of Tomorrow EP Marc Guggenheim, who now serves as an executive consultant on both shows, for some of the nostalgic Easter eggs.

As for the decision to take the team to the familiar farm to meet with Kara and her equally-heroic cousin, Clark Kent (Tyler Hoechlin, reprising his role as The CW's Superman), Supergirl EP Robert Rovner noted, "We felt [it was a good place] to reset them."

"Kara’s dealing with stuff in the aftermath of our midseason finale," he explained, "Clark has been on Argo City, so it felt like a great place for them to reconvene and figure out their problems together. And to meet Lois."

Grimm alum Bitsie Tulloch made her first appearance as The CW's Lois Lane on Sunday's episode, introducing the intrepid reporter as Clark's formidable other half. Rovner raved that bringing the iconic couple together on screen once again was an "amazing" experience.

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"We’ve dreamed of having Lois Lane be on Supergirl. We’ve talked about her since the beginning," he recalled. "So that was great. 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, and that was thrilling."

Tulloch will return for part three of the crossover on Tuesday's special episode of Supergirl, but as for bringing the character back in future episodes, Rovner remained hopeful.

"Bitsie Tulloch is great at embodying everything that is iconic about Lois, and we just love ‘em together," he noted. "I think the plan was for her to be in this, but if DC allows and the story takes us, we would love to have her back."

The actress told ET last week that she'd love to return as well, raving about the experience of playing one of the DC Comic canon's most iconic women.

"One of the reasons I love the character is that she has qualities of being so career-driven and determined and sassy and almost a little bit aggressive when she's on a mission, but also really romantic and sweet and so in love with Clark," she noted. "All of that came through in the writing. These are big episodes... [but] it was definitely enough to get the point across to the fans that this is her personality and this is what she represents and adds to the equation."

Night two of the crossover, a special episode of Arrow, will find the still-swapped Barry and Oliver traveling once again -- this time to Gotham City to meet another new face in the DC Comics TV canon: Ruby Rose's Batwoman.

Caroline Dries, who is executing producing Rose's Batwoman standalone series, noted that the crossover event is a full-circle moment for some of the shows' producers, who also worked on Smallville and longed to dive deeper into the DC universe.

"All of a sudden, we can do stuff [we weren't allowed to before] and, for a bunch of geeks like us, you’re in heaven," she marveled of creating a new version of Gotham for the small screen. "It’s [all about] trying to figure out what you want to use. That was really fun, I think, for everyone."

The Elseworlds crossover continues Monday with Arrow and Tuesday with a special episode of Supergirl, both at 8 p.m. ET/PT on The CW.