The final scene, in which Giles walks into a tree, was not in the shooting script. It was a last minute addition by Anthony Head, intending to provide the scene with more comic relief.
According to Jane Espenson, the fact that Joyce and Giles had sex under the influence of the chocolate bars in Band Candy (1998) was confirmed because she was shocked fans still weren't sure about it.
We learn in this episode that Sunnydale High has a high enough mortality rate for the school newspaper to run a regular obituaries section.
The Sunnydale High School clock tower was constructed especially for this show. It will be seen only one more time in Graduation Day: Part 2 (1999).
When the gang are together in the library, Oz thinks to himself "I am my thoughts. If they exist in her, Buffy contains everything that is me, and she becomes me. I cease to exist". This is a nod to French philosopher René Descartes, who came up with the Latin phrase "Cogito, ergo sum" which translates to "I think, therefore I am". Descartes used it to prove his own existence, claiming his ability to form thoughts made him a real, living, human being. On her DVD commentary, writer Jane Espenson says that Joss Whedon suggested Oz's reaction by telling Jane to "write him something that sounds like something Friedrich Nietzsche would have said in the situation."