During the initial airing of this episode the Joker refers to Harley Quinn and Poison Ivy as busy little beavers; it was changed to busy little bees during later airings. The original line actually made it in, but the staff decided they'd gone too far and chose to alter at the last minute.
The friendship between Harley Quinn and Poison Ivy proved to be such a popular addition to the animated continuity, it was also adapted into the comic books continuity.
The three frat boys that harass Harley Quinn and Poison Ivy at the stop light are producers Bruce Timm (incorrectly given red hair), Eric Radomski and background supervisor Ted Blackman.
Poison Ivy injects Harley Quinn with a toxin antidote to allow her to stay on the toxic waste dump. Later this is found to have also increased Harley's strength and stamina. Because of this, she survived greater falls suffered in Mad Love (1999) and in Batman Beyond: Return of the Joker (2000).