Nicholas Brendon was sick with pneumonia for part of the filming, so his twin brother, Kelly Donovan stood in for him for the part of Xander Harris.
Jane Espenson explains the Buffybot was introduced out of "the necessity of story", as it was "interesting to see what Spike would do with this bot... to see how those personalities affect each other." Providing Sarah Michelle Gellar with the chance for comic relief during a period of particular grimness for her character was a "bonus... an extra scoop of ice-cream," says Espenson.
The Buffybot pronounces "Giles" with a hard g (as in "guy-els"). Joss Whedon and Marti Noxon have said on several occasions that they get annoyed with "so-called fans of the show" when they pronounce "Giles" in this way. This pronunciation is present as well in some official international dubbing for the series.
To call upon the guide, Giles reads in Swahili: "...nilivyoahidi kulinda na kuongoza, nakupokeza. Mpeleke afike mahali pa usalama na ujuzi. Mpe anavyohitaji. Mwonyeshe njia." This translates to English as: "...that which I am pledged to guard and guide, I hand over to you. Lead her to a place of safety and learning. Give her that which she needs. Show her the path..."
When it's revealed to the group that there are two Buffys, Xander says, "Hey, I know this! They're both Buffy!" This is a reference to The Replacement (2000), in which Xander's psyche was split into two separate bodies.