- The Cast Showoff: Sarah Thompson sings "LA Song", which was written by series co-creator David Greenwalt and Christian Kane for Lindsey McDonald to perform on-stage in "Dead End". Thompson, who grew up doing musical theater, had begged Joss Whedon to allow her character to sing.
- Completely Different Title:
- Czech: "Démon starí ne sám čas" (A Demon Older than Time Itself)
- Finnish: "Maailmassa on reikä" (There's a Hole in the World)
- German: "Illyria"
- Hungarian: "A szarkofág" (The Sarcophagus)
- Creator's Favorite Episode: Alexis Denisof and Amy Acker named this as one of their favourite episodes, with Denisof calling it "the most difficult, but also satisfying and heart-rending day at work".
- What Could Have Been:
- The original idea for the episode saw Angel and Spike fly out to England to see Giles, as Joss Whedon needed someone who both the characters and the audience would believe when he told them that there was no way to save Fred. The limited budget prevented them from flying in Anthony Stewart Head for a cameo, though (ironically, from England), so the character of Drogyn was invented as being physically unable to lie.
- Joss Whedon had planned for Fred to return in season 6, fighting Illyria for control of her body. Unfortunately, the show was cancelled, and so Fred remains dead and even, as we learn in the next episode, deprived of an afterlife, which comes off as quite pointlessly cruel if you don't know the behind the scenes story.
- Write What You Know: Joss Whedon revealed that the "astronauts versus cavemen" discussion that reoccurs throughout the episode is based on something written on the idea board in the writer's room.
Trivia / Angel S 05 E 15 A Hole In The World