The Live With Kelly and Ryanco-hosts rang in the holiday by paying homage to some of pop culture's most unforgettable viral moments and trends, featuring live costume changes including Baby Shark and a burger and fries a la Katy Perry and Taylor Swift in the latter's video for "You Need to Calm Down."
Celeb appearances were aplenty as well, with Jimmy Fallon, Josh Groban and Liza Koshy making cameos and Kal Penn even sitting down for an interview while in costume, first as Baby Shark and later as Taco Belle.
ET was on the set of Live for the festive episode to get a first-hand look at how Ripa and Seacrest manage to pull it all off.
"It seems like we've been shooting this for a month," Ripa told ET's Rachel Smith.
"I thought Halloween had happened already," Seacrest agreed with a laugh.
Ripa went on to share that her own preparations extended up until the night before, when she was fitted for her Barbie on roller skates costume.
"We thought we were done and I said, 'We're done with the Halloween show. All we have to do is come out in our cowboy outfits, right?'" Ripa recalled. "And then... our producer said, 'What are you talking about? We have so much we haven't done yet.'"
"Last night I was still in a wardrobe fitting and I thought, 'This cannot be happening,'" she added.
Seacrest, he said, wasn't clued in on the entirety of his coordinating Ken costume until the morning of the show.
"This they didn't reveal it to me. They just showed me the shorts. Then they showed me all this at once this morning," he said with a grimace. "...This is a lot of trouble. Lots of badness. It's terrible."
"This is what I've been waiting for all my life," he added with mock seriousness. "This big reveal."
The biggest challenge of the whole thing for Ripa came during the transformations from "hideous to beautiful" as part of the taped segments, one of which featured the Property Brothers and Mark Consuelos in an Addams Family home improvement sketch.
"[My makeup artist] had to take me from [Regan from] The Exorcist... to Morticia [Addams]. It was going from hideous to beautiful to hideous to beautiful, and it was back-and-forth," she said. "And I said, 'We should've done beauty first and then hideous.' He was a genius and he had his work cut out for him, because he does it so fast."
For Seacrest, though, it was his own makeup work that he found challenging, when -- in one of the taped segments in which he and Ripa played horror movie characters acting out viral challenges -- he channeled a beauty vlogger giving a tutorial on how to go from Pennywise to the Joker.
"Going from Pennywise to the Joker in my own tutorial of my channel -- subscribe! -- was tricky," he admitted. "That was hard. I had never done a tutorial."
One thing Seacrest didn't find tricky, though, was his epic dance number while rocking the Billy Ray Cyrus costume that complimented Ripa's Lil Nas X ensemble for the pair's tribute to "Old Town Road."
"I let [the music] inspire," he quipped. "And that's what music should do. It should inspire America."