Two of the show's writers, David Fury and Marti Noxon, have small singing parts. Fury can be seen singing "They Got the Mustard Out" outside the magic shop when Buffy checks to see if other people are singing. Noxon sings about a parking ticket ("I think that hydrant wasn't there") while Giles, Xander, and Anya are walking on the street after Xander and Anya's duet.
Preparing for the episode was physically difficult for some of the cast members, most of whom had little experience singing and dancing. They spent three months in voice training. Two choreographers worked with Joss Whedon and the cast on dance sequences. Michelle Trachtenberg, who is trained in ballet, requested a dance sequence in lieu of a significant singing part and Alyson Hannigan, according to Whedon, begged him not to give her many lines. Sarah Michelle Gellar told the BBC that "It took something like 19 hours of singing and 17 hours of dancing in between shooting four other episodes" and she was so anxious about singing that she "hated every moment of it". When Whedon suggested using a voice double for her, however, she said, "I basically started to cry and said, 'You mean someone else is going to do my big emotional turning point for the season?' In the end, it was an incredible experience and I'm glad I did it. And I never want to do it again."
Fans continued their appreciation in theater showings where attendees are encouraged to dress like the show's characters, sing along to the musical numbers, and otherwise interact in the style of The Rocky Horror Picture Show (1975). Clinton McClung, a New York-based film programmer, got the idea for a sing-along from audience-participation showings of The Sound of Music (1965) in 2003. The next year, he began putting on sing-alongs in Boston's Coolidge Corner Theater, which became so popular that it went on the road. Audience members received props to use during key scenes, as well as directions (for example, to yell "Shut up, Dawn!" at Buffy's younger sister), and a live cast performed the episode alongside the screen.
The sing-alongs received growing media attention as they spread. At the 2007 Los Angeles Film Festival, a special screening and sing-along was held that featured both Marti Noxon and Joss Whedon giving brief speeches to the audience. In October 2007, after a dispute with the Screen Actors Guild over unpaid residuals, 20th Century Fox pulled the licensing for public screenings, effectively ending official sing-alongs. Whedon called the cancellation "hugely depressing" and attempted to influence the studio to allow future showings.
Joss Whedon says his biggest surprise in terms of musical ability was Emma Caulfield Ford, while he knew that James Marsters, Amber Benson and Anthony Head were very skilled singers by their former performances.
On the DVD commentary for this episode, Joss Whedon says that many of the songs he wrote for this musical were conscious references to different musical theater styles and composers. For instance, Whedon characterizes "Going Through The Motions" as an "I want" song in the tradition of the opening numbers sung by heroines of Ashman-Menken Disney musicals such as "Part of Your World" from The Little Mermaid (1989) and "Belle" from Beauty and the Beast (1991) (albeit with what he calls a Stephen Schwartz ending). He says that "I'll Never Tell" is his 1930s "Astaire/Rodgers" number, and he likens "Walk Through The Fire" to the four-part "Tonight Quintet" that introduces the climactic moments of the end of the first act of "West Side Story."