The Doublemeat Palace is shown for the last time on Willow's Macbook for a few seconds, as she is looking through the camera feeds.
When Willow and Tara talk at the university, Tara wears the leather jacket Dawn attempted to give to Buffy in Older and Far Away (2002).
Anya mentions to Buffy her former lovers, but Buffy counters with that "there have only been four- three! Three! Three guys." This line refers to Buffy's past sexual partners Angel, Riley Finn, Parker Abrams, and (secretly) Spike.
Halfrek explains to Anya that vengeance demons are unable to enact wishes on their own behalf. In the comic Own It, Part Four, D'Hoffryn will attempt to remove this limitation from their powers.
Dawn argues that the Scoobies patrolled since they were her age (16), which Buffy says it's true, but claims that she's technically one and a half years old, since she was first created as a human in Buffy vs. Dracula (2000).