Trivia: In the final episode when Buffy, Xander, and Willow are wandering off talking about shopping, Giles turns round and says "The Earth is definitely doomed!" This is a little tribute to the end of the episode 'The Harvest' when Buffy, Xander and Willow wander off talking nonsense and Giles turns round and says a similar thing.
Trivia: This is the only episode to feature the lead actors from all four of Joss Whedon's Mutant Enemy productions: Sarah Michelle Gellar (obviously), David Boreanaz guest starred as Angel, Nathan Fillion (from "Firefly") played Caleb, while Eliza Dushku, who played Faith, was the lead on "Dollhouse".
Trivia: Except for Buffy, all of the First's incarnations at the end of the episode are the previous seasons' Big Bads, in reverse chronological order: Warren (season 6), Glory (season 5), Adam (season 4), Mayor Wilkins (season 3), Drusilla (season 2), and The Master (season 1).
Trivia: Anyone who has read some of the BtVS books will notice that the background plot for season 7 (killing all the Potential Slayers and then the actual Slayers to end the line and let evil rule) is the plot of the book Pretty Maids All In A Row - Spike and Dru are trying to do just that.
Trivia: Willow's conversation with a dead person in this episode is with Cassie, of which it is explained that Willow isn't allowed to see Tara because she killed people. In actual fact, the writers did intend for Tara to appear in this episode, however actress Amber Benson was busy with other filming commitments.
Trivia: Xander was originally supposed to be the character that died in Chosen. He was suppose to die saving Dawn. Since Emma Caufield didn't want to be tied to doing any future Buffy projects the script was changed so that Anya would die. The script is the same except the parts at the end written for Anya and Xander were switched as well as the parts for Andrew and Dawn.
Trivia: Obvious with hindsight, but less so at the time. Kennedy is later revealed to be gay, and her interest in Willow is hinted at but not stated outright. However, when all the potentials are playing with the weapons, Rona grabs a stake, saying "I like the feel of wood in my hand". Kennedy arrives mid-way through that line, and says "lost me there". Possibly her thinking it's just a "middle of the conversation" comment, or just a blatant indicator of her sexual preference.