- Creator's Favorite Episode: Mark Hamill has often stated that this episode has his favorite Joker scene where the Clown Prince of Crime delivers a eulogy to supposed dearly departed Arch-Enemy, highlighting the need for the Joker to have Batman.
- Inspiration for the Work: Bruce Timm stated that the idea for the episode came when he and Paul Dini debated on what it would be like if Batman was not present for the majority of the episode. Indeed, it is one of the most-acclaimed episodes of the series.
- One-Take Wonder: Harley performing "Amazing Grace" on the kazoo was done by Arleen Sorkin in one take. In an interview, Paul Dini stated that it was fortunate that Sorkin was able to complete the song in one take, as immediately after that, she and the remainder of the voice cast also broke into uncontrollable laughter, and "we'd have never gotten a second take of it".
Trivia / Batman: The Animated Series E51 "The Man Who Killed Batman"