The D23 Expo in Anaheim, California, is the kind of place designed to make Disney fans squeal with delight. After all, the Expo, which happens every two years, is like an exclusive Disney version of Comic Con. At D23, there are panels devoted to your favorite Disney TV shows, movies, and parks; plus signings and memorabilia and all of the other things you expect from a glossily produced extravaganza put on by a global media titan.

At all of the panels, the fans are primed to go nuts. But I have never heard applause like that which greeted a "Ralph Breaks the Internet" sequence that was shown at 2017's D23 Expo. It was insane.

The sequence involved Vanellope (Sarah Silverman) visiting the Oh My Disney website, which is devoted to all things Disney. (So, essentially, a digital version of the D23 Expo.) It's there that she runs into the canonical Disney Princesses -- including Cinderella, Aurora, Ariel, Belle, Jasmine, Pocahontas, Mulan, Rapunzel, Merida, Anna, Elsa, and Moana. All of whom are voiced by the original actresses, who, true to show-stopping Disney dazzle, walked out on stage, arm in arm, at the D23 Expo right after the footage was shown.

The Disney Princess sequence is laugh-out-loud funny, to the point that it was hard to hear some of the jokes, but also genuinely subversive and something of a technical achievement, since many of these characters were traditional, hand-drawn characters being rendered in CGI for the very first time. (There had been prototypical 3D models built for Mickey's PhilharMagic, an attraction that opened at the Magic Kingdom at Walt Disney World, and subsequently at Hong Kong Disneyland and Tokyo Disneyland. It just debuted at Disneyland Paris in early Oct. 2018.) I remember my jaw dropped when I noticed that Pocahontas' hair is continually blowing in the wind.

And, it turns out, it took a lot to bring all this to the big screen.

At a recent long-lead press day for "Ralph Breaks the Internet," there was a presentation on the sequence, with co-writer Pamela Ribon, art director Ami Thompson, and head of animation Kira Lehtomaki breaking down the particulars of a sequence that, pretty soon, everyone will be talking about.

In 2014, Ribon started working on the film's story treatment and she returned to it a couple of years later (after the production's entire team was pulled into the production of "Zootopia," an all-hands-on-deck type situation that worked out quite nicely). Ribon admitted to being nervous about "Ralph Breaks the Internet," considering how sacred the characters are. She was instructed by director Rich Moore: "I think we just board it and see what happens." (Sequences are storyboarded before being animated.)

Once they began storyboarding the sequence, it was clear that it was working. They somehow managed to squeeze in a joke about how Merida is from Pixar and not Walt Disney Animation Studios; she's the only outsider Princess.

And what's more, Ribon, who is a Disney Princess diehard, provided the Snow White voice during the scratch sessions and wound up voicing her in the movie. Talk about magical!

Designing the sequence proved just as tricky. For one, the sequence features 14 (!) classic Disney Princesses, many of them having to be redesigned for the format and all of them interacting for the first time. (The Disney Princess product line has strict guidelines for how the Princesses acknowledge one another. If you look at any box art, none of them are making eye contact, but seem to be sharing physical space.) Thankfully, they had an all-star team on the Princesses' design team, including designers Cory Loftis, Brittney Lee, and Lorelay Bove.

And always willing to lend a hand was Mark Henn, the original Disney animator behind most of the modern Disney Princesses (Jeffrey Katzenberg once referred to him, somewhat strangely, as "The Julia Roberts of Animation"). Thompson trained with Henn and said that he was always there to help. Henn also created the animated Sorcerer Mickey that sits atop the virtual animation building at the top of the scene. And, if you'll recall earlier this fall, Anika Noni Rose had a meeting at Walt Disney Animation Studios about how her character was being modeled in "Ralph Breaks the Internet," and one of the people she met with was Henn, who animated Tiana in "The Princess and the Frog."

The fact that Henn created the original characters and advised on their new incarnations is just part of what makes Walt Disney Animation Studios (and the Princess sequence in "Ralph Breaks the Internet") so special.

Additionally, the Princesses were all given what are being referred to now as their "comfy clothes;" dressed-down versions of their iconic royal looks. Thompson said that they had to adapt each Princess' signature style to "internet language" (perfect for a movie all about the Internet), hence why Moana is wearing a shirt that reads, simply, "#Shiny." (If you want to know how lucrative just the new looks for the Princesses will be for the company, stop into your local Disney Store the next time you're at the mall.)

Animating the Disney Princess sequence was also challenging, for obvious reasons. Lehtomaki, a self-described "Disney hoarder" (she was wearing Toms emblazoned with original Cinderella concept art), worked with Henn on the sequence, learning how he "performed" the characters in the earlier masterpieces and bringing her own flair to the characters. Henn was an invaluable resource, having "acted" many of these parts before, for their classic films. The weight of the sequence was immense, since, as Lehtomaki said, it was required that "every moment feels true to who they are." And it's true -- one false note would have made the entire, painstakingly produced sequence crumble. Talk about pressure.

And maybe most tantalizingly of all, Lehtomaki teased that the sequence that they showed at the 2017 Expo -- and has been featured in much of the marketing materials thus far -- isn't the only one to feature the Princesses.

"You'll see more of them," she said. Can you imagine what the response to that would have been at the D23 Expo?