The episode begins and ends in the same place, Joe's Tavern, which is opposite the Gotham Hotel where Harley Quinn and Poison Ivy were staying.
The three late-night revelers singing "Auld Lang Syne" in the tavern are caricatures of Bruce Timm, Glen Murakami, and Shane Glines.
The Batgirl/Clayface story was originally published as a comic book story, then later adapted for the series.
The toy store where Batman chases Harley and Ivy is Wacko Toys, the same company that made Riddler puzzles and games in the Batman: The Animated Series (1992) episode "Riddler's Reform (1994)".
The football game that Joker's message interrupts features a commentator naming one of the players as "Altieri", a reference to Kevin Altieri.