Michael Jackson called Matt Groening and requested to voice a character on the show. He was a big fan of Bart and promised to write a number one song for him. The song he wrote, "Do the Bartman", reached number one in many European countries in 1991.
Michael Jackson performed the speaking voice of Leon Kompowsky under the pseudonym John Jay Smith. Although he was able to lend his voice to the speaking parts of a character, the record company would not allow him to sing. As an alternative Jackson entrusted Kipp Lennon, a founding member of the folk band Venice, with the job of the singing parts of the character. Lennon has contributed to several episodes of the series.
This was the second time that a major celebrity guest appeared on the series. The first was Dustin Hoffman who appeared in The Simpsons: Lisa's Substitute (1991) credited as "Sam Etic". Following Jackson's use of a pseudonym, the producers no longer allowed celebrities to use fake names.
Matt Groening has confirmed that Michael Jackson did provide the voice (under the name John Jay Smith) for Leon Kompowsky. He did not do any singing which was done by an impersonator. Jackson wanted an impersonator to sing because he wanted to fool his brothers into thinking the impersonator was him. Jackson did record himself singing but the tracks were not used.
There is a phone number on a box of cereal, "1-909-O-U-CLOWN", that was supposed to be a parody of a 900 number. Approximately one year after the original airing of this episode, area code 909 went online in Southern California. Although a 2003 re-airing showed the number, a re-airing in 2009 later blurred out the number as by then it was a real number in service.
In the original script when Leon Kompowski speaks to Bart over the phone and identifies himself as Michael Jackson, Bart sarcastically asks, "And is Prince with you?" The reference was changed to Elvis Presley at the request of Jackson.
According to Al Jean, Michael Jackson would not commit to the episode until after a read-through of the script was done. The read was held at Jackson's manager Sandy Gallin's house, and Dan Castellaneta (who provides the voice for Homer) was 30 minutes late. Jean recalls that "no one said a word, we just sat there waiting". Following the read, Jackson stipulated his conditions: he would record his speaking parts but not receive credit, and his singing voice would be performed by a sound-alike.
The episode originally was supposed to end with Kompowsky singing a portion of "Man in the Mirror" in his Michael Jackson voice as he walked down the road, but it was changed to him singing the beginning of "Happy Birthday Lisa".
The original airing had an introduction which was a dig at President George Bush's comments (saying that American families should be "more like _The Waltons_ and less like The Simpsons"). The family is sitting in front of the TV watching Bush's speech, and Bart fires back with, "Hey, we're just like The Waltons; we're praying for an end to The Depression too!"