The term "Scooby Gang" is used for the first time, when Xander tells Cordelia "You want to be a member of the Scooby Gang, you gotta be willing to be inconvenienced every now and then."
When Xander and Cordelia break into Buffy's house, the scenes were filmed on location in the actual house. By the time production had begun on What's My Line?: Part 2 (1997), they had moved to a replica sound stage. The only noticeable difference is the windows on either side of the front door. When Cordelia lets Norman Pfister into the house, you can see the windows are standard glass with curtains. However, in Part Two they are slim panes of non-see through glass.
The Tarot cards that Drusilla consults are not real ones. Writer Marti Noxon had no idea what images were used on real Tarot cards so she just made up whatever images were necessary for her plot.
Darla asks Angel in Angel (1997) if he believes Buffy would ever be able to kiss his "real face." She does so here.