Al Kapone's involvement in the film came from a case of mistaken identity. Director Craig Brewer was expecting a phone call from DJ Paul (Paul Beauregard) because he wanted to hire Paul to write the songs that DJay would perform. Kapone, who knew Brewer from the Memphis music scene, decided to call him at that very same time. He told Brewer that the movie needed to have his music in it and Brewer immediately agreed. After a few minutes of small talk, Brewer realized he was talking to the wrong person. Too embarrassed to back out of the deal, Brewer told Kapone that he could audition with one song. Kapone had only 24 hours to write a song for DJay. He was sent the script by courier and was given Terrence Howard's phone number to discuss the character. The next day, Kapone performed "Hustle & Flow (It Ain't Over)" for Brewer and producer John Singleton. They loved the song so much, they used an additional three of Kapone's songs for the soundtrack.
While filming in Memphis, Tennessee, Anthony Anderson and assistant director Wayne Witherspoon were arrested and charged with sexual assault on a woman who Witherspoon allegedly lured to a production trailer. Charges against Anderson were later thrown out by the presiding judge.
Terrence Howard interviewed 123 pimps and 78 prostitutes over a period of two and a half years. This process included living with four separate pimps for various periods, including a month-long stint in a Memphis bordello.
There are numerous references to Memphis-based musicians in the film: The character of Shelby was named after Shelby Bryant, a singer-songwriter from Memphis. In one scene, Shelby is wearing a T-shirt with the logo of Sam Phillips's Memphis Recording Service studio. In another scene, Shelby wears a T-shirt of Lucero, a local country-rock band. Many of the studio musicians who played for Stax Records, the legendary Memphis-based record label, play on the original score. Isaac Hayes, who plays Arnel, recorded for Stax Records. The cover of the 1974 Stax album "Victim of the Joke?" by Memphian David Porter is stapled to DJay's work table. Otis Redding, who also recorded for Stax Records, is mentioned in one scene. Al Green's song "Jesus is Waiting" is heard during one scene. Memphis native Josey Scott of the band Saliva, appears as a store owner. Members of the popular rap group Three 6 Mafia appear in the film. Paul Beauregard plays DJay's neighbor and Jordan Houston plays Skinny Black's brother. Haystak, Free Sol and Al Kapone are local rappers who appear in the film.
Craig Brewer added several touches from his personal life in the script: his wife worked in a strip club, then got pregnant, he would have to turn off the air conditioning to edit or the fuse would blow out and he actually saw a black pimp with a white braids-wearing hooker in a car trying to hustle up some business near a local hotel.
Although there are numerous references to famous Memphis-based musicians in the film, Craig Brewer deliberately avoided any direct references to Elvis Presley. In an interview, Brewer said: "That was a rule. No Elvis."
After winning the Oscar for Best Original Song, host Jon Stewart jokes that Three 6 Mafia is ahead of Martin Scorsese in terms of Oscar wins. Scorsese would later win his Oscar for directing "The Departed" in his decades-career.
Terrence Howard is the only actor to ever appear in two films to receive an Oscar nomination for Best Original Song in the same year. This film won the award for "It's Hard Out Here for a Pimp." The other nominated song was "In Too Deep" from the Best Picture winner Crash (2005).
Terrence Howard and Ludacris also appeared in Crash (2004) the same year this film was released. Both films were released just two months apart. Hustle & Flow (2005) opened on July 22, 2005 while the latter film _Crash (2004)_ opened on May 6, 2005. The latter film "Crash" would go on to win Best Picture at the 2006 Academy Awards.