The Joker steals an atom bomb, so Batman and Robin must team up with Harley to find him and stop him.
- Auction of Evil: For the atomic bomb.
- "Bang!" Flag Gun: Joker goads Harley Quinn into trying to shoot him, but it turns out the gun is of the stick-with-a-"bang"-flag variety. The Joker is still impressed that she pulled the trigger. (Though the Joker didn't know the gun was a fake, either.)
- Don't Touch It, You Idiot!: After Harley Quinn wants to listen to the Batmobile's radio and presses a button that instead expels the Batmobile's parachute.
Batman: Listen, and listen good. You don't touch anything, say anything, or do anything unless I tell you! Got it?
Harley: (small voice) Yes, sir.
- Berserk Button: Harley don't appreciate to see her Mr J. attacked, but even him hasn't immunity about her "babies" (their hyenas).
- Foreshadowing: Early on, when the mayor is on the phone, one can see that his sleeve is purple...
- Iris Out: A heart-shaped one.
- Noodle Incident: Harley and Boxy Bennett apparently had a history together.
- Slip into Something More Comfortable: Harley Quinn takes Batman back to the Joker's last hideout to look for clues. Once there, she says, "Have a look around while I slip into something more comfortable," and changes out of her Arkham jumpsuit and into her regular costume.
- The Villain Sucks Song: Technically, the torch song Harley Quinn sings is one, but because of the nature of her relationship with the Joker, it's also a twisted love song.