The movie is dedicated to Alexa Kenin and Bruce Weintraub. Kenin, who played Jena, was murdered in New York City just before the movie was released. Set Decorator and Production Designer Weintraub (who had been Oscar-nominated for Prizzi's Honor (1985)) died of AIDS at thirty-three. This was the last movie on which he worked before his death.
When the ending was re-shot, all of the principal cast members had to be called back. Andrew McCarthy had already lost a substantial amount of weight and shaved his head for a new role in a New York City play called "The Boys of Winter". Although he wore an auburn wig, he's noticeably more gaunt in the re-shot scenes.
The Rave-Ups are the band playing in the club scene. Molly Ringwald was apparently a fan of their music, and her sister had a child with one of the band members. Also, in Sixteen Candles (1984), "The Rave-Ups" is scrawled on the notebook Sam (Molly Ringwald) is carrying while walking down a corridor after study hall.
In spite of their chemistry on-screen, Jon Cryer (Duckie) has stated that both of his co-stars Molly Ringwald (Andie) and Andrew McCarthy (Blane) found him "irritating" from day one. Cryer, who describes himself as a "very outgoing person" believes his attitude was the reason he never got along with the very reserved Ringwald and McCarthy.
The filmmakers wanted Blane, to be "a hunky, square-jawed jock," but Molly Ringwald wasn't attracted to that sort of guy. Ringwald had some say in the casting, and after Andrew McCarthy auditioned, she told John Hughes and Howard Deutch her thoughts on him. "That's the kind of guy I would fall in love with." They thought he was a "twerpy guy", and weren't interested, but Ringwald pushed for his casting.
"If You Leave" was not the original song Orchestral Manoeuvres in the Dark had composed for this movie. Their song "Goddess of Love" was the original composition, but it did not fit when the ending was changed.
When James Spader auditioned for Howard Deutch and John Hughes, he completely immersed himself in the jerky character of Steff. He smoked a cigarette in the room, and crushed the cig on his way out. Hughes and Deutch almost didn't cast him until they realized just how much he embodied the role. After Spader got the part, Jon Cryer complimented Spader's prior works. "I figure I got a lock on this teenage a**hole thing," Spader told Cryer.
Duckie's dance was originally set to "State of Shock" by Mick Jagger and Michael Jackson. When the filmmakers couldn't get the rights to the song, it was changed to "Try a Little Tenderness" by Otis Redding. Jon Cryer suggested both songs.
Kristy Swanson's film debut. She was recommended by John Hughes for the non-speaking role of Duckette, who only appears in the re-shot ending. Hughes had liked her when she played a small role in Ferris Bueller's Day Off (1986), which was released later in 1986.
The trivia items below may give away important plot points.
John Hughes was unhappy with the ending. He wanted Andie to get together with Duckie. But the film's ending of Andie getting together with Blaine was forced upon him by the studio. In retaliation, Hughes virtually made the same film all over again the following year with Some Kind of Wonderful (1987), a film about a similar love triangle. Hughes wanted Molly Ringwald to star in it as well, but she refused. Hughes took it personally, and effectively ended their working relationship. They never worked together again.
Robert Downey, Jr. was almost cast as Duckie, when the ending had Andie getting together with Duckie. Per Molly Ringwald, this ending may have stuck if Downey won the role, because he didn't give her the "brother vibe" Jon Cryer did.
In 2010, for the 20th Anniversary of Entertainment Weekly Magazine, EW reunited Molly Ringwald, Jon Cryer, and Annie Potts for a photo shoot and interview. The three discussed what they thought their characters lives were like after the movie ends. Ringwald said that she thought Andie and Blaine would have broken up shortly after the end of the film, but Andie and Duckie would have remained lifelong friends, and also that Duckie would have long since come out as gay.
The original ending to this film depicted Duckie getting the girl. However, the test audiences said they would have preferred to see Blane win Andie's heart. Additionally, Molly Ringwald was sick during the filming of the ending, and John Hughes wasn't satisfied with the editing. He was also concerned that audiences would take the original ending as a message that poor people and rich people don't belong together.
A novel for the film was adapted and released in the same year of the film's release. H.B. Gilmour was the author. The book was written before the last scene was changed, so it has the original ending, in which Andie picks Duckie over Blane.
When Andie and Duckie are in the car driving home, Duckie is changing radio stations. The song with the saxophone that he changes before he says "I hate this song", is the same song ("If You Leave" by Orchestral Manoeuvres in the Dark) that plays at the end of the film, when Andie chooses Blane over Duckie at the prom. This could be seen as foreshadowing what would happen at the prom.