The Bus Came Back: Boxy Bennett, the crooked owner of a Gotham City nightclub, made a brief appearance in "Harlequinade" and returned her. There's even a Continuity Nod to "Harlequinade", with Boxy grumpily reminding Harley that his place got trashed the last time she visited him.
Continuity Nod: Boxey points out that the last time Harley Quinn showed up at his door she not only destroyed his club, but brought Batman down on him as well. This occurred in "Harlequinade," where Harley was helping Batman find the Joker.
Doomed New Clothes: Veronica Vreeland. There she is, buying a new dress for her date with Bruce Wayne and along comes a spooked Harley Quinn. Her car gets ruined, too. Considering that Veronica actually got taken hostage by Harley, she probably wasn't too concerned about the car at first.
Dungeon Bypass: Harley's hyenas burst through a wall to attack Boxey after Harley calls for them.
Hey, Wait!: Harley Quinn meets Bruce Wayne and covers the top half of his face, saying she recognises that chin. Bruce thinks he's been found out, but it turns out it was actually Bruce Wayne she was recognising by his chin.
Limited Wardrobe: Bruce actually goes suit shopping with Veronica Vreeland, who points out that Bruce needs a better sense of style
Miranda Rights: The ever-cynical Detective Bullock warns Boxey Bennett, "You have the right to remain silent, if you choose to give up that right, you're probably going to bore me to death, so just shut up."
Tank Goodness: Harley Quinn ended up being chased by one driven by General Vreeland after accidentally kidnapping his daughter Veronica.
(while driving away) Veronica: Wait-what are you doing? That's my father. Harley Quinn: No, that's your father, IN A TANK!