Whether you call it a romantic comedy, a science fiction movie, a dark character drama or something else entirely, there's no denying that "Eternal Sunshine of the Spotless Mind" is one of the great American films of the 21st Century. Celebrate the 15th anniversary of this Michel Gondry classic with some interesting facts you might not have known.

1. The original screenplay depicts Clementine as becoming more emotionally withdrawn and robotic with each memory erasure. However, Kate Winslet opted to portray Clementine in a more straightforward fashion.

2. Writer Charlie Kaufman became disillusioned when Christopher Nolan's "Memento" hit theaters and offered a similar premise revolving around memory loss. Producer Steve Golin convinced him to finish the screenplay anyway.

3. Gondry purposely worked to keep star Jim Carrey off-guard during production, including forbidding him from improvising and rolling the camera without telling Carrey. This was intended to help Carrey get into character as the nervous, uneasy Joel Barish.

4. Gondry originally envisioned Nicolas Cage for the lead role, but found Cage to be in high demand in the wake of "Leaving Las Vegas."

5. For the scene in which Mark Ruffalo's Stan startles Kirsten Dunst's Mary, Gondry instructed Ruffalo to find a different hiding spot for each take in order to ensure Dunst remained genuinely scared each time.

6. The film was parodied by "The Simpsons" in an episode called "Eternal Moonshine of the Simpson Mind." That episode won an Emmy award in 2008.

7. The opening credits don't appear until a full 18 minutes into the film.

8. Winslet relied on a series of wigs rather actually dyeing her hair. Because of Clementine's constantly changing hair color and the nonlinear order in which the film as shot, dyeing would have been impractical.

9. The street parade sequence was unplanned and conceived on the spot. Because of this spontaneity, TV reporters appeared and attempted to interview Carrey during the middle of filming.

10. The film features relatively little CGI for a sci-fi project. Even the scene of the house being washed away by the ocean actually required a partial set to be constructed on a beach.

11. Gondry cut an entire subplot from the film involving Joel having a one-night stand with his ex-girlfriend Naomi (played by Ellen Pompeo).

12. The film's title comes from the Alexander Pope poem "Eloisa to Abelard," which was also featured in Kaufman's previous screenplay, "Being John Malkovich."

13. While it's no longer active, a fully functional website was created for fictional corporation Lacuna Inc.

14. In October 2016, Golin's production company Anonymous Content and Universal Cable productions announced an "Eternal Sunshine of the Spotless Mind" TV series, though the series has yet to materialize.