The trivia and goofs have mostly been taken from TV.com.

# During the filming of the dressing room scene, Joss Whedon was so impressed with David Boreanaz's reflection in a mirror that he planned to go from Cordelia to Angel's reflection and had to be reminded by the crew that Angel was a vampire, and therefore wouldn't appear in the mirror at all.
# Charisma Carpenter has studied classical ballet since the age of five -- was Cordelia's profound boredom with the production a touch of insider irony?
# Fred and Gunn kiss for the first time in this episode.
# The idea for this episode came about when Amy Acker mentioned to Joss Whedon that she used to be a Ballerina. Eager to show off her talents on screen, Joss wrote this episode with a dream sequence where Fred and Wesley replace the two leads. He was reportedly gutted when the scene he had written the whole episode around had to be removed. Luckily for fans, the scene has seen the light of day on the "Angel" Season Three DVD.
# It's interesting to note that Summer Glau, who plays the Prima Ballerina, goes on to star in "Firefly," another Joss Whedon created show. # The first episode of Angel written by creator Joss Whedon since the pilot. Expect Buffy references and rejected musical ideas.
# Mark Lutz is not listed in the opening guest star credits so that Groosalugg's return at the end of the episode is a surprise.
# Angel refers to the Buffy the Vampire Slayer

# If you look in the bottom right corner of the screen when Angel and Cordelia are having sex, you can see part of Charisma Carpenter's nipple.
# WWhen Angel and Cordy are in the ballerina's dressing room, his tie goes from crooked when Angel is enmeshed with Cordy, and then straightens itself out without him touching it in the next shot.