So Damon Lindelof is a huge Phineas and Ferb fan. The Lost co-creator and screenwriter behind films like Prometheus has a thing for the Disney XD show about two kids and their seemingly endless summer. For instance: he knows where kind-of villain Dr. Doofenshmirtz’s money comes from.

“I don’t remember which episode it was, but the subject was raised as to how he was able to afford all of his [inventions],” Lindelof recalled. “And he sort of said ‘Off of his alimony checks. Which kind of tells you everything you need to know.'”

And that’s how you get a pseudo-Lost crossover with jokes riffing on some of that show’s notorious mysteries as well as Lindelof’s own relationship with Internet-age audiences and their need for finality and closure in their fiction.

Lindelof laughed then, saying that he discovered the show through his school-aged son, getting mired in its weird continuity (the elder Lindelof will go on and on about the show’s mysterious floating baby head), even moderating one of the show’s Comic-Con panels two years ago (“It was just a fancy way to get my questions answered,” Lindelof joked).

Lindelof joined Phineas and Ferb co-creators/producers Jeff “Swampy” Marsh and Dan Povenmire for the intimate premiere of the episode while answering press questions about “Lost in Danville,” which Lindelof provided the story for.

The 11-minute episode – making its debut this week on Disney XD – sees secret agent Peter the Panda getting his own nemesis in a mysterious figure voiced by a Mad Men performer who I won’t spoil here. Lindelof told us that the idea for the episode actually came from a conversation with his son who wanted to know who the ex-nemesis of Dr. Doofenshmirtz could possibly be. Meanwhile, in the B story, a mysterious capsule lands in Phineas and Ferb’s backyard – one with an even more mysterious hatch.

“We knew that there would be people who would watch the episode specifically because of Damon,” Marsh told us, adding that they free to riff on ideas from Lost based on Lindelof’s story. “There’s a lot that [Damon] threw in that allowed us to have fun with that.”

Lindelof says working with Marsh and Povenmire was “a dream come true,” given his love of the show. “I think one of the most exciting times in my career was being in a place where I felt slightly uncomfortable and having to please my bosses [Povenmire and Marsh].” He continued “I think one of my strong suits is not comedy, but I loved [this].” “His Twitter feed notwithstanding,” Marsh quipped.

Marsh added that it was Lindelof’s idea to make the episode about communication – and how a breakdown in communication can end up with a body finding themselves on the wrong end of a spare nemesis (leading, improbably, to a riff on Billy Joel’s “Tell Her About It”).

Lindelof went on to say that he was intrigued by the idea of an episode where the villain keeps withholding details of his master plan (much to everyone’s frustration).

As for that mystery Mad Men performer, Povenmire says it was a joy having him in the booth recording lines. “He was another one of those folks that when you get him into the booth, you realize how cool he thought it was to be there doing cartoon voices,” Povenmire told us. He added that that kind of thing is fun for the people making the show because when the talent is into it, they’re “willing to try weird stuff” with their characters while in the booth.

You can see that mystery performer and the mysteries of the mysterious capsule when “Lost in Danville” premieres Monday, September 29 at 7:30 PM ET on Disney XD.