The mention of Superman being in Argo City ties in to "Elseworlds, Part 3 (2018)"; at episode's end, he and Lois reveal to Kara that Lois is pregnant, and Clark is taking her to Argo so she can deliver the baby safely.
The title of this episode is taken from Superman IV: The Quest for Peace (1987), where Jon Cryer (Lex Luthor in Supergirl) played Lex Luthor's nephew.
Sharing the same name as the film, Superman IV: The Quest for Peace (1987), the episode shares a plot point. At the end of the movie, the Superman clone Nuclear Man, created by Lex Luthor, is dropped into a nuclear power plant causing its power output to skyrocket. It's played as a bit of joke. On Supergirl Lex Luthor uses a Supergirl clone and tons of other aliens as the power supply for power plants, playing the same idea seriously.
For Cryer, Lex was a role that he took without reading it, diving in without even knowing exactly where things would go. "No, I didn't know, because this is one of the roles, I took without reading it," Cryer said. "Jessica [Queller] had told me a little about what they wanted to do, sort of bare bones, but for me, I really had to wait until I got the actual words, and so, okay, who is this guy and what does he talk like? I had to wait until I saw that, to figure out where we wanted to go. I mean, we talked about who we loved, and obviously, we loved [Gene] Hackman and I was a big fan of Michael Rosenbaum from Smallville. It was never quite articulated. We always kind of left it up in the air and said, 'Let's see where this goes.'"
In a post to Twitter, Cryer thanked the cast, crew and more for all their hard work on the series, as well as for the version of Lex the writers built for him to bring to life. He followed it up with a thank you to fans for giving him a chance, especially since there were initial reactions that Cryer was an "odd" choice for the villain role. However, Cryer smashed all expectations, delivering a Lex Luthor to the Arrowverse that hit all the right notes. Cryer's performance was so impressive, it also earned praise from Michael Rosenbaum, who portrayed the baddie on Smallville and is for many fans the standard for the role.