Sarah Thompson sings "L.A. Song", which was written by David Greenwalt and Christian Kane for Lindsey McDonald to perform on-stage in Dead End (2001). Thompson, who grew up doing musical theater, had begged Joss Whedon to allow her character to sing.
Feigenbaum, Fred's stuffed bunny, is named after Mitchell Jay Feigenbaum, a mathematical physicist, who did pioneering studies in chaos theory.
The scene where Gunn is fighting himself in the White Room was done by filming J. August Richards twice in two shots, as he switched between good and evil Gunn. Richards says of the experience "It was one of the most fun things I've ever done on the show."
While in the hospital, Fred says "handsome man saves me" referring to her first meeting with Angel in Through the Looking Glass (2001).
When Knox is looking for a way to cryonically freeze Fred, Gunn says to Knox "You got me all up in this Walt Disney mojo." He's referring to the well-known urban legend that Walt Disney's body was cryonically frozen.