OC Hardcore musicians worked as extras.
The hardcore punk scene is famously against neo-Nazis, with bands who sing about unity and audience members who violently eject racist skinheads - or "boneheads," as traditional skins like to call them - from clubs and festivals. Funnily enough, a few notable members of the Orange County hardcore community worked as extras in American History X, thanks to the amount of fashion the boneheads have notoriously lifted from the largely anti-racist subculture. Sharp-eyed hardcore fans will spot members of OC bands like 1134, Mean Season, and The Third Degree.
The director spent a year recutting the movie.
New Line wasn't satisfied with the first cut of American History X and sent notes to the director, who spent a year working on a second version. In 2002, he told the UK's Guardian, "I found a whole new film, one that they never allowed me to finish."
Edward Norton oversaw the final cut.
Edward Norton sat with editor Jerry Greenberg working on what became the third and final cut of American History X, after New Line rejected Tony Kaye's second version. Kaye went through the roof, punching a wall and breaking his hand. He took out dozens of full-page ads in the Hollywood trades, lambasting the studio and quoting William Shakespeare and John Lennon in the process. He stomped on a VHS copy of Norton's edit and tried to flush the pieces down a toilet. In one meeting with studio executives, he brought a rabbi, a priest, and a Tibetan Buddhist monk to help.
Tony Kaye tried to have his name removed from the credits.
Kaye was so dissatisfied with the postproduction process and the final cut of the film that he tried to have his name removed from the credits, invoking the old Directors Guild of America practice of swapping a director's name with the pseudonym "Alan Smithee." The DGA rejected this idea, on the grounds that Kaye had already disparaged the movie in public, which is something "Smithee" users shouldn't do. Kaye asked to have his name switched to "Humpty Dumpty" instead, even threatening to legally change his name to that. He sued New Line for $200 million.
Norton's cut is 20 minutes longer than the original.
Ultimately New Line was able to release their preferred version of American History X. Kaye has said Norton added those additional bits of footage in order to give himself more screen time. Somewhere, there's an unreleased documentary featuring footage Kaye filmed himself during the whole tumultuous process, which a much more measured Kaye has said he'd like to see included in future Blu-ray editions. After torching so many relationships in the industry, Kaye didn't make another movie for many years. At one point, he befriended screen legend Marlon Brando, who hired him to a series of acting seminars called Lying for a Living. Tony Kaye never finished that project. The fact that he showed up for work dressed as Osama bin Laden, less than two months after 9/11, didn't do his reputation any favors. As for Norton, it's probably worth noting that he rewrote the script for The Incredible Hulk and had a heavy hand in the postproduction process. The version of the movie preferred by him and the director was 23 minutes longer than the one Universal insisted on releasing instead. Norton did not return to play the Hulk again.