 Whedon chose the most complicated scene , with the most dancers and choreography in the classic style of musical theater , to accompany an 18 @-@ second song ( " The Mustard " ) " to get it out of the way " for more personal numbers later in the episode . Stephanie Zacharek of Salon.com considers this " brilliant because it frees even people who hate musicals to settle into the story without getting hung up on the genre 's conventions " . The musical styles span from a jaunty 1950s sitcom arrangement of the Buffy theme in the opening credits — the only episode in the series to begin without the normal version of the theme song and full cast roll , signifying a genre shift — to Anya 's hard @-@ rock version of " Bunnies " . Whedon assigned Emma Caulfield the rock @-@ opera format because Caulfield often sang in such a way to him on the set . Spike 's " Rest in Peace " is also a rock song , which Whedon wrote after completing the episode 's first song , Tara 's " Under Your Spell " , a contemporary pop song with radio @-@ play potential . Xander and Anya 's duet — the most fun to shoot but difficult to write , according to Whedon — is inspired by Fred Astaire @-@ Ginger Rogers comedies as evidenced by the silken pajama costumes and art deco apartment setting . Musically , the song uses influences from Ira Gershwin , a Charleston rhythm , and jazz @-@ like chord slides . Giles ' " Standing " is a ballad to Buffy that she does not hear , unlike the songs revealing truths elsewhere in the episode . Whedon shot the scene so that Giles moves in real time while Buffy works out in slow motion , to accentuate Giles ' distance from her . Buffy 's not hearing his song was intentional ; Whedon explained , " you can sing to someone in musicals and they can never know how you feel or how much you love them , even if they 're standing right in front of you " . 
