Micheal Jackson is credited as John Jay Smith because contract obligations prevented the show from confirming that the real Micheal Jackson was the voice of Leon.

Blackboard Joke: I am not a dentist.
Couch Gag: The family run to sit on the couch which tips over backwards slowly. As they go through the wall, the couch rights itself.

According to DVD commentary, there was originally supposed to be a sequel to this episode, where Leon Kompowsky (the mental patient who thinks he's Michael Jackson) returns, now thinking he's Prince, and rallying the town into being sexually uninhibited. The episode idea fell through when the real Prince refused to do voicework for it (though the premise of Springfield acting uninhibited would later be used for the season five episode "Bart's Inner Child").

This episode reran on July 5, 2009 at 8:00pm in memory of Michael Jackson (who died a week before this episode reaired).

Bart: Hey, we're just like the Waltons. We're praying for an end to the depression, too.

Marge: Oh my God, Mother was right!

Leon Kompowsky: Hi. I'm Michael Jackson, from The Jacksons.
Homer: I'm Homer Simpson, from the Simpsons.

Announcer: Our $50,000 home video finalists are...Man Breaking Hip. (sound of bowling pins falling, followed by a scream)
Homer: (laughs)
Announcer: (chuckling) Dog On Fire. (using a doggy voice) Ruff, anybody order a hot dog?
Homer: (laughs loudly) Oh, look at him!
Announcer: And finally, Baby With a Nail Gun. (gun fires)
Homer: Aww....
Announcer: Okay, it's time to cast your votes now!
Homer: (excitedly) Dog On Fire! Dog On Fire!

Bart and Michael Jackson (Leon)'s song to Lisa:
Lisa, it's your birthday.
God bless you this day.
You gave me the gift of a little sister, and I'm proud of you today.
Lisa, it's your birthday.
Happy birthday, Lisa.
Lisa, it's your birthday.
Happy birthday, Lisa.
I wish you love and good will.
I wish you peace and joy.
I wish you better than your heart desires.
And your first kiss from a boy.
Lisa, it's your birthday.
Happy birthday, Lisa.
Lisa, it's your birthday.
Happy birthday, Lisa.

Homer: Lisa you like homework, could you fill out this form for me?
Lisa: Well, alright. If you listen to the poem I just wrote.
Homer: D'oh! Okay.
Lisa: I had a cat named Snowball, she died, she died. Mom said she was sleeping, she lied, she lied! Why, oh why is my cat dead? Couldn't that Chrysler hit me instead? (Pause) I had a hamster named Snuffy, he died--
Homer: No deal!

Michael Jackson: Homer, this is Floyd. He’s an idiot savant – give him any two numbers and he can multiply them in his head, just like that.
Homer: OK, 5 times 9!
Floyd: 45.
Homer: Wow.

Right when Mr. Burns sees that Homer is wearing a pink shirt to work, when he pauses and zooms in, Homer is looking almost directly at the camera. In the next shot, though, he is looking more toward his left. The people surrounding him change as well.

When Bart says "Krusty Hotline," his mouth does not move.

When Bart and Michael are playing a song to Lisa, Bart uses his bin as a drum. Sometimes you hear tapping, even though Bart doesn't touch the bin.

One Flew Over the Cuckoo's Nest

Several of the elements of the plot and characters and events that take place in the asylum are taken directly from the classic 1975 film, One Flew Over the Cuckoo's Nest.

Rain Man

The idiot savant Homer meets at the hospital, who can multiply very complicated numbers in his head, is a parody of Dustin Hoffman's character in the 1987 film.

The Silence of the Lambs

The man with a leather mask is a parody of Hannibal Lecter from the classic 1991 film.