Sharon Horgan talked unsexy sex and Carrie Fisher cracked wise about “Stars Wars” at the Tribeca Film Festival’s Tribeca Tune-In event for Horgan’s buzzy Amazon series “Catastrophe” — but only after Fisher’s dog, Gary, stopped throwing his weight around.

The pup (38 pounds, to be exact) makes several scene-stealing appearances in both seasons of “Catastrophe,” and looked like he would walk away with the Tribeca panel discussion too. But once he had a few biscuits and settled down for a nap, Horgan and Fisher could at last reveal some behind-the-scenes secrets about the show — including why season two starts with a time-jump that finds the central couple three years and two kids along in their marriage.

When asked by moderator Alex Jung what prompted the jump, Horgan explained, “When we originally pitched the show, it was the second season. We had a little bit of the meet-cute — I’d never heard that term before — but that all happened in the first episode, and then at the very end [of the episode], we flashed forward three years and there we are, bang in the middle of the just awful hell of long-term marriage and children. Our commisioners in the U.K. thought it was a good idea to spend a bit of time with them, and get to know the couple. It gave us our first season, and it was fun. … But then when it came to the second season, we just didn’t love the idea of having a new baby, and being the couple that doesn’t know how to deal with the new baby. So we thought, Let’s just go back to our original idea. We didn’t know how people would respond, but it made it interesting for us.”

Horgan said she and co-creator Rob Delaney got the idea to cast Fisher as Delaney’s mother when the two of them saw Fisher showing off her comic chops at an event with Graham Norton. “I said, ‘That’s my awful mother-in-law!'” Horgan remembered, before turning to Fisher and saying, “We didn’t think for a minute you’d do it.”

For Fisher, the role appealed to hear as something different. “I did want to play an awful person, instead of carry guns and talk to Harrison all the time,” she joked.

That wasn’t her jab at “Star Wars” at the panel. Fisher became a writer, she said, after she was asked to deliver awkwardly written lines — such as “I have placed information vital to the survival of the Rebellion into the memory systems of this R2 unit.” (She still knows the full line; she said it twice.)

Now, with “Catastrophe,” she’s finding herself upstaged by Gary. “He was recognized yesterday, and not me,” she told Horgan. “I’m not kidding. From your show!”

When Jung asked Horgan how to write a sex joke, she quipped, “I think it’s very hard to not write a sex joke,” before continuing, “The thing is for it to feel real, not corny. And not trying to be sexy is the thing. If we ever tried to make our sex scenes sexy, it’d be the end of us.”

Horgan and Delaney write every episode of “Catastrophe.” “We just sit side by side and we start talking,” Horgan said. “I tell him horrible stories from my life, and he tells me horrible stories from his life.” Inspiration comes from “listening to people on the bus, and stealing my friends’ stories.”

But now that Horgan has worked with a writer’s room on “Divorce,” the upcoming HBO show she created for star Sarah Jessica Parker, she might consider bringing more writers aboard for “Catastrophe.” She’s hesitant, though, because “Catastrophe” comes from very personal territory.

Does that mean that TV Rob and TV Sharon are a lot like real Rob and real Sharon? “We decided that they’re nicer than us,” Horgan joked.