Sometimes Buffy the Vampire Slayer (1997) writers include in-jokes in their scripts. The shooting script for this episode contained the following direction: "A couple of soldiers pass. Xander suavely nods to them. They nod back and pass without comment, because they are extras." When Xander and Cordelia make out, the directions were: "They haben der big smoochen."
Angel turning bad after sleeping with Buffy was one of the solutions the writing team came up with to counter the potential Sam and Diane fall-out that often happens in TV shows when two leading characters finally get together. (The general consensus is that Cheers (1982) took a nosedive once Sam and Diane became lovers.)
The trivia item below may give away important plot points.
The woman whom Angel kills shortly after losing his soul is played by Sophia Crawford, who was the stunt double for Sarah Michelle Gellar for the show's first four seasons. This was the only time on the show when her face was shown (intentionally).