- Acclaimed Flop: Its theatrical run was not very financially successful, largely attributable to its unusual, difficult-to-market premise and the fact that it was given a limited theatrical run because it came out shortly after 9/11. Critics reacted well to it, however.
- Actor-Inspired Element: Noah Wyle deciding his character was diabetic (watch for the Jolly Rancher candies).
- Big Name Fan: Christopher Nolan, just off of directing Memento, liked the movie enough to convince Newmarket Films to distribute it (which distributed Memento). Had he not stepped in, it would have gone straight to Starz and debuted on cable.
- Breakaway Pop Hit: Gary Jules' stripped down, Softer and Slower Cover of Tears for Fears' "Mad World" is arguably more popular than the film it came from.
- Dawson Casting: Sort of. Jake Gyllenhaal was nineteen playing a sixteen-year-old. Maggie Gyllenhaal was twenty-three - though it's not stated exactly what age Elizabeth is supposed to be. Averted with Jena Malone, who was still a teenager.
- Deleted Scene: An alternate ending, where Donnie dies by being impaled on a post.
- Doing It for the Art: Drew Barrymore liked the project so much that she stepped in with her production company to finance it - effectively saving it from being released direct-to-video. She also took a small role as Karen Pommeroy.
- Life Imitates Art: The film was shot in twenty-eight days - the exact amount of time the story covers.
- One-Hit Wonder: Richard Kelly directed two other movies afterwards, but they both got poor reviews and aren't well remembered today. Likewise, the soundtrack's most famous song, the cover of "Mad World", is Gary Jules' only claim to fame and composer Michael Andrews' only chart presence.
- Playing Against Type: Patrick Swayze, known for playing smooth heroic types, as a sleazy motivational speaker who is also a child molester.
- Real-Life Relative: Brother and sister Donnie and Elizabeth Darko are played by brother and sister Jake and Maggie Gyllenhaal.
- Star-Making Role: This is the film that launched Jake Gyllenhaal's career.
- Throw It In!: Donnie correcting Gretchen was due to Jena Malone struggling to pronounce Dr Kenneth Monnitoff's name.
- Vindicated by Video: The film's cult really grew once it hit video, and with the internet becoming more commonplace led to various message boards and fan sites being created. Home video sales eventually led to the film making its money back and spurred the creation of the (contested) Director's Cut.
- What Could Have Been:
- Mara Wilson was apparently given a script to read for a role in the movie, but was evidently freaked out over the Mind Screw of a script at a time she was already physically ill in her hotel room in England, and passed on the role as a result. And now she plays The Faceless Old Woman Who Secretly Lives In Your Home in the equally Mind Screwy Welcome to Night Vale.
- Richard Kelly originally wanted Tim Robbins for Eddie Darko.
- Vince Vaughn was also the first choice for Donnie, but declined since he was almost thirty. Mark Wahlberg expressed interest in playing Donnie too, but only if he could give the character a lisp.
- Donnie's sexual fantasies in the original script were to be about Alyssa Milano. For "legal reasons" it had to be changed to Christina Applegate.
Trivia / Donnie Darko