Marks the first time Harley Quinn appears without the Joker.
The diploma stamped "SANE" Harley displays from Arkham Asylum is signed by "K. Altieri". Kevin Altieri is the episode's director.
Harley Quinn's sense of déjà vu when she sees Bruce Wayne is not unique; Joker likewise thought he recognized Bruce in Joker's Wild (1992).
Harley and Batman both talk about having a "bad day." This may be a reference to the ground-breaking comics story 'The Killing Joke' by Alan Moore, in which the Joker sets out to prove that "one bad day" is enough to make anyone as crazy as him.
The fighting moves used by Robin spinning two fishes against two villains is the same moves used by Bruce Lee during his climatic showdown with two nunchucks in Enter the Dragon (1973).