In the previous episode, before getting them to agree to marrying each other by threatening to destroy Luthor Family Children’s Hospital, Rhea tells Mon-El and Lena Luthor that they will get married -- to symbolize a union between Earth and Daxam -- and produce an heir.
Seeing as though Lena has no interest in knocking boots with her best friend's boyfriend no matter how handsome he is, she highly doubts Rhea will be able to force her and Mon-El to procreate. However, Mon-El explains, "She doesn't need us for anything. She just needs our genetic materials. Daxamites can generate a child using just locks of hair." And then Rhea reveals that she collected locks of their hair while they slept.
While speaking with Katie McGrath, EW asked the Irish actress if viewers should be worried that Rhea has already produced or will produce a Mon-El/Lena child.
"I am not going to lie to you, we had these conversations on set," McGrath replied with a laugh. "What’s great and what’s difficult about a show like this is that as a cast, you are as much kept in the dark about details as you’re going along, which makes it exciting to read a script, and frustrating when you don’t already know. Things like that come up and the writers are very clever at giving tiny little seeds, tiny little hints that at the time you’re like, “Hmm, that’s not important,” and then becomes a major plot point. As a result, all of us in it, we question everything. We’re like, “Is this important?! Is this going to become a person in the next season?!” We don’t know! I’m thinking, “Are we going to see this, ultimately amazing, child?” Can you imagine? We don’t know, but wouldn’t it be interesting? It would be interesting to the relationship between Kara and Lena, for Mon-El and Kara, for everyone involved if we saw that. But I don’t know. You’d have to ask Andrew [Kreisberg], and if he told you and not me, I would be really pissed. [Laughs]"
Supergirl (Melissa Benoist) challenges Rhea (guest star Teri Hatcher) to battle to save National City. Meanwhile, Superman (guest star Tyler Hoechlin) returns and Cat Grant (guest star Calista Flockhart) offers Supergirl some sage advice.
Glen Winter directed the episode with story by Andrew Kreisberg & Jessica Queller and teleplay by Robert Rovner & Caitlin Parrish.
Distributed worldwide by Warner Bros. International Television Distribution, SUPERGIRL is executive produced by Greg Berlanti (Arrow, The Flash), Ali Adler (The New Normal), Andrew Kreisberg (The Flash, Arrow) and Sarah Schechter (Blindspot, The Mysteries of Laura). Supergirl is based on the characters created by Jerry Siegel and Joe Shuster and appearing in DC Comics, by special arrangement with the Jerry Siegel Family.