To prove to Willow that he's the real Xander, he does the Snoopy Dance, which Willow noted she likes seeing him do when she goes to his house to watch A Charlie Brown Christmas (1965) in Passion (1998).
The "hasty" Xander brushes off Willow's remark, that he did not think earlier about the implication of the situation with Anya, by wondering how she would handle an evil twin. Willow mutters "Well I handled it fine," a reference to her her counterpart from the Wishverse she faced in Doppelgangland (1999).
Xander gets a promotion at his construction job, he's shown as presumably a foreman, which is the beginning of Xander being shown to have more responsibility on construction sites in later episodes. In Once More, with Feeling (2001), he tells Anya he had to shut his own crew for the day; in Lessons (2002), he arrives wearing a suit; and, in Showtime (2003) he indicates he may be responsible for multiple construction sites too.
Xander mentions Buffy had been in hell, a reference to the factory dimension she went in Anne (1998).
Riley mentions Buffy's obsession with bad ice skating movies. Buffy's interest in ice skating has been previously mentioned in episodes like What's My Line?: Part 1 (1997).