Warner Bros. Pictures

Wednesday marked the day we'd all been looking forward to, the 15th birthday of the 2002 Scooby-Doo movie. While you may have thought America's favorite film had been utterly strip-mined for trivia, screenwriter James Gunn has some new info about a long-gone tidbit, the one about how Scooy-Doo could have been rated R(ut-roh) instead of PG.

Marvel's prized Guardians of the Galaxy–whisperer was doing his first script with a major studio, a few years before his directorial debut, Slither. On Facebook, he shared a long note that featured this near the top:

"Yes, it was not exactly what we planned going out—I had written an edgier film geared toward older kids and adults, and the studio ended pushing it into an clean cut children's film. And, yes, the rumors are true—the first cut was rated R by the MPAA, and the female stars' cleavage was CGI'd away so as not to offend. But, you know, such is life. I had a lot of fun making this movie, regardless of all that. And I was also able to eat, buy a car, and a house because of it."

Sarah Michelle Gellar also spoke long ago about a same-sex kiss between her Daphne with Linda Cardellini's Velma getting cut despite being an actual important plot point.

Gunn wrote about being hit hard by the "pretty terrible" reviews. "These days I might glance at the occasional review (admittedly, mostly only good ones), but back then I read EVERY. SINGLE. ONE. I also read everything written about the movie online, by, like, anybody, including bulletin board folks."

Then Saturday morning came, Gunn got a call saying that Scooby's $18 million opening Friday and broken a June record. (It wrapped with $276 million worldwide.) "Until that moment, I thought if the movie came out and didn't do well I'd be able to continue getting writing jobs, and my life was going to be the same," he wrote. "But in that one single moment I knew everything had changed. And it did. I was offered every movie you can imagine."

Including The Jetsons. Oh, what could've been. Still, Gunn ended up coming back for Scooby-Doo 2: Monsters Unleashed two years later. It was rated PG and didn't earn much more than half the American gross of the original.

Last fall, after three years in the works it was announced Dax Shepard will co-direct a new animated Scooby-Doo feature with Space Jam artist Tony Cervone. It was set for 2018 and quickly bumped back to 2020. It's being viewed by Warner Bros. as  “our first shot at unlocking the whole Hanna-Barbera Universe.” They did just hire the director of Sausage Party for The Jetsons...

Watch The Blacklist actor Amir Arinson talk about his time as an official touring real-life Scooby-Doo: