Spoilers below for the Season 1 finale of HBO Max's The Flight Attendant, so be warned!
Considering the Kaley Cuoco-showcasing new series The Flight Attendant is just as much a murder-mystery as it is a dark comedy, there aren't a whole lot of easy ways for the HBO Max series to directly reference Cuoco's former hit sitcom The Big Bang Theory. (The same definitely goes for her animated series Harley Quinn.) That said, fans thought they'd found just such a specific Big Bang easter egg in The Flight Attendant's recently aired Season 1 finale, but it turns out the moment was just a big coincidence.
In the midst of the episode "Arrivals and Departures," Kaley Cuoco's Cassie Bowden was in Rome and made a frantic return to her hotel room accompanied by her occasional friend-with-benefits Enrico (Alberto Frezza). Just before Enrico went to go back downstairs to nab Cassie a coffee from the hotel bar, she gave him instructions on what to do when he returned so that she would know it was him. And that's where the theoretical Big Bang Theory callback comes in, as seen below.
As just about every Big Bang Theory fan out there is well aware, Jim Parsons' Sheldon Cooper was known for rapping on doors in three-knock cycles, with Penny's apartment door getting the lion's share of Sheldon-specific knocks, especially early on. As such, it would have been a perfectly understated reference to Kaley Cuoco's former show had that line been intentionally written with the CBS hit in mind. But that wasn't so much the case, as showrunner Steve Yockey explained to Glamour:
It was not. You’re watching with a powerful investigative lens! But maybe it should be. But no, it was not intentional.
It's kind of a bummer to know that know, even though The Flight Attendant's central story would have gained absolutely nothing from a random Big Bang Theory reference popping up just ahead of the finale's most hectic confrontation. But who doesn't love a good easter egg that complete sense within the context of the scene its introduced in?
While The Flight Attendant's knocking line may not have been a purposeful link back to Kaley Cuoco's past, Steve Yockey & Co. did make the decision to cast the actress' sister Briana Cuoco, who appeared in a single Big Bang Theory episode. (Season 6's "The Tangible Affection Proof," for those keeping score.) For this latest role, the younger Cuoco sibling played Miranda's not-altogether-trustworthy colleague Cecilia, and Yockey spoke with TVLine about making the decision to cast her for the role, which was not influenced by Kaley herself.
When we cast Bri, Kaley was like, 'Listen, I’m not going to weigh in on this because I don’t want to tip it [as an EP].' Cecilia is one of my favorite characters because she doesn’t have a lot of real estate, but she packs a wallop in terms of personality, and when Bri came in and read for it I was like, 'Yes.' She has that spunk. The character went through three different style iterations, in terms of trying to find what gives us the best impact, and so we changed her costume, and then tried something different, and it was great because Bri was so game to go along with everything. She was having a good time and always ready to work. That’s what I look for when we’re casting people.
Given how The Flight Attendant's first season ended, we could very well see Bri Cuoco's Cecilia again whenever Season 2 takes to the air in 2021 or later. Maybe when Steve Yockey and his creative team are knocking out those follow-up scripts, they can have Cassie calling everybody "Sweetie" for a little while, or she temporarily lives in a building where the elevator is always broken. Or they can cast Johnny Galecki, because why not?