As reporters arrived in the room at Comic-Con International, the stars of It’s Always Sunny in Philadelphia -- Danny DeVito, Charlie Day, Glenn Howerton, Kaitlin Olson and Rob McElhenney – were already comfortably seated, and talking and laughing with each other. They were clearly friends hanging out, and not just actors working together.

When the series returns Sept. 4 for its ninth season, it will be on FX’s new comedy channel FXX, but the cast reiterated that nothing else has changed about the show.

DeVito called the new season “completely off the charts,” and wondered what Day, Howerton and McElhenney did in their private lives to come up with some of the storylines. For instance, one episode will find his character Frank trapped in a coil on a playground wearing nothing but his “tighty-whities.”

In real life, Olson (Dee) is married to McElhenney (Mac), while Day (Charlie) is married to Mary Elizabeth Ellis (the Waitress) -- and Howerton’s wife guest-starred in an episode as Dennis’ girlfriend. So when asked whether Rhea Perlman will ever make an appearance on the show, DeVito said, “If something came along that was right for her, she’d do it.” However, she’s busy with a new show starring Kirstie Alley.

When asked if they ever go back to watch themselves in old episodes, McElhenney shared, “It depends on the mood I’m in, but I always take pride in what we do.” Day added, “Now, if someone had taped one of my plays from college, I’d be uncomfortable watching that!”

A lot of details were revealed about the new season, which includes a Thanksgiving episode that features the return of many guest stars as the gang tries to make amends to the people they’ve hurt. Gail the Snail, Charlie’s apartment manager Wang, Bill Ponderosa and many others will appear.

Another episode will feature Sean William Scott in the role of Country Mac, the cousin to “City” Mac. Another surprising guest star will be Josh Groban, whom Howerton shared “is hilarious, a great improviser.”

As reported earlier, Season 9 also includes an episode written by Game of Thrones creators David Benioff and D.B. Weiss, who reached out to McElhenny and Day. “Their perspective is fascinating,” Day said.

Lethal Weapon 6 also returns as the gang makes another sequel to their favorite movie. This time, Dee has a part to play, but to the shock of the other characters, she’s actually a good actor – so good that they cut her out of the majority of the movie, leading to some funny sequences.

Olson hurt herself during the first take when she slipped into a hole and sliced a huge gash in her leg that kept her off the set for a week.

Howerton, who was in the scene with her, ran to help. “I asked if it was broken, and she goes, ‘No! It’s a blood thing,’” he said. Olson joked, “I’ve had two babies, it wasn’t that bad.”

The last big reveal of the day was a small one, but a fun one: In a recent episode, Mac’s real name was revealed to be Ronald McDonald, something the actors had thought up years ago in Season 2 but waited to reveal it until recently. At first, it was just a joke between them, but over time it became the character’s real name.