In the flashback scenes, Niles (David Hyde Pierce) wears the same striped button-down shirt that he wore in nearly every episode of Seasons 1, 2, and 3 of the series.
Mongolian throat singing is a real art form called Tuvan. Groups do perform the technique, though not for four hours at a time. It has also been incorporated into certain rock bands, and it has spawned its own heavy metal rock group, The Hu.
The celebrity caller in this episode is Anthony Edwards, playing Tom, who calls from his wedding to say he's having second thoughts.
Martin has the neon sign from Duke's bar underneath his mirror in his bedroom.
While Martin and Roz are having a discussion in his bedroom a small portrait can be seen at the side of his bed. It's a picture of Rita Wilson, who occasionally portrays his deceased wife Hester.