Throughout the DVD commentary, both Cameron Crowe and John Cusack kept returning to a phrase that summed up the philosophy of Lloyd Dobler and the movie as a whole: "Optimism as a revolutionary act."
There's a fascinating backstory to Say Anything: Cameron Crowe had written a forgotten teen movie called The Wild Life (with Chris Penn, Eric Stoltz, and Ilan Mitchell-Smith, of Weird Science fame) that he wasn't so fond of, but iconic television creator/producer James L. Brooks ("Taxi," "Mary Tyler Moore," "Lou Grant") saw it and thought there were some really nice moments. So, Brooks met with Crowe and asked him to write a more personal movie. He didn't set a timeline on it. They'd get together occasionally to discuss it. During these meetings, Cameron would basically talk about what was going on in his life with his wife, Nancy Wilson (of Heart fame), and a lot of what came out of those conversations was inserted into Say Anything.
Lawrence Kasdan was originally set to direct, but he balked.
Robert Downey, Jr. turned down the role of Lloyd Dobler, which eventually went to John Cusack, though Christian Slater was also under consideration.
Jennifer Connelly nearly got the role of Diane Court, which went to Ione Skye.
Lloyd Dobler was based on a neighbor of Cameron Crowe's, Lowell Marchant, who came to his door one day and introduced himself, saying he was a kickboxer and that kickboxing was the sport of the future. Lowell had this "stoic noble thing,' and he was very polite, and would wipe his hands off on his pants before he shook your hand. James Brooks told Crowe to write that guy. And from that moment on, Lloyd took life, basically created from the mannerisms and spirit of Lowell.
Crowe had John Cusack in mind when he wrote the part but felt that Cusack probably wouldn't take it. In fact, Cusack hadn't originally planned to take the role because he wanted to stop making high-school movies, but saw "a harbinger of soul" underneath the standard milieu, as well as Crowe's passion for the project. Once they started "riffing together, it was kind of inevitable."
Interestingly, Cusack turned Crowe on to The Replacements, whose lead singer, Paul Westerberg, was instrumental in the soundtrack for Crowe's next movie, Singles.
Cusack knew Lili Taylor before the film because Lili Taylor used to go out with Cusack's friend D.V. DeVincentis, who would later write High Fidelity and Grosse Point Blank.
Stone Gossard (at the time, with Mother Love Bone, later Pearl Jam) had a tiny cameo as a cab driver who checked out Diane Court.
In addition to being the character who threw the graduation party, Eric Stoltz was also the 'celebrity P.A." on the set; he literally fetched coffee for Cusack because he wanted to experience all facets of filmmaking.
Lili Taylor's character, Corey, was based on an actual woman named Corey who had an actual obsession with a guy named Joe.
Julia Roberts came up twice for the role of the "third friend' to Corey (one of the girls who basically sits around Lili Taylor's character while she plays "Joe Lies' and obsesses over Joe); that role eventually went to Amy Brooks. In one version of the screenplay, the friend and Lloyd had a moment.
Among the extras in the movie are Barbara Streisand's son (who played the drunk guy that had to be driven home), David Lee Roth's daughter, Chynna Phillips (who played Joe's girlfriend), and of course Jeremy Piven (who Cusack calls "Gerald," which I believe was Piven's nickname).
Loren Dean (Mumford) (who played Joe) first came up for the part of Lloyd.
Joan Cusack, who plays Lloyd'd sister in the movie, came in and did the movie unbilled.
Before filming, when Cusack was developing the character, he wrote out a "manifesto," which was several pages long. One of the items on that manifesto was the "bought, sold, processed" line that ended up in the famous dinner table speech.
Ione Skye was quite turned on by Cusack during the car driving scene, saying that -- if they didn't have a boyfriend and girlfriend in real life at the time -- that's the day they probably would've gone home together. Apparently, however, Ione's real-life boyfriend waited around her trailer all day, "which was really annoying." Ione says that, in another life, she and John would've been a "great love." In several points during the commentary, Ione and Cusack confessed romantic attraction toward one another during filming.
The scene, after the break-up, where Cusack is bummed out and talking to his friends up against the fence (including Piven): Those were Cusack's real-life friends (minus Loren Dean), and because the studio wouldn't do it, Crowe and Cusack paid to fly them out from Chicago for that scene.
There are a lot of stories about what the song was supposed to be during the boombox scene. As it was originally written, it was going to be Billy Idol's "To Be a Lover." The actual song playing during filming was Fishbone's "Turn the Other Way." A few songwriters were commissioned to come up with a song (including The Smithereens), but none of them worked. Eventually, Crowe found "In Your Eyes" on a wedding tape that he'd made for his own wedding to Nancy Wilson.
During the scene in which Cusack was kick-boxing (before Diane confessed that she loved him), Cusack was completely hung over because he'd gotten trashed with Jeremy Piven the night before.
The last scene, which ends with a close up for Lloyd and Diane, was an homage to The Graduate.
The studio had very little faith or interest in the movie until Siskel and Ebert gave it two thumbs "way up."
After opening night, Cameron and Cusack were hanging out at a bar, and an excited woman came up to Cusack and said, "Are you Lloyd?" Cusack responded, "On my better days, yes." Crowe would later use that line in Almost Famous, when someone approached Russell Hammond and asked, "Are you Russell Hammond,' and he responded, "On my better days, yes."