These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Adaptation Displacement: Not the movie itself, but the song "Mad World", which is played over the credits. That version is sung by Gary Jules, doing a cover, causing many people not born in The Eighties to think he is the original artist, rather than Tears for Fears.
Misaimed Fandom: The film is frequently labeled, for better and worse, by emos and emo-haters, as one of the most emo films of all time. It's actually a massive deconstruction, especially the Director's Cut.
They Changed It, Now It Sucks: The Director's Cut gets a lot of flak for replacing the opening song The Killing Moon with Never Tear Us Apart. Nevermind the fact that the only reason the theatrical cut didn't open with the latter was that Kelly couldn't secure the rights for the song at the time. Furthermore, The Killing Moon was not actually removed from the Director's Cut - the song is played in its originally intended sequence towards the end of the film, where it arguably packs an even greater punch.
Vindicated by History: Did poorly in theaters, largely because it debuted about a month after the September 11 attacks note even worse, the plot involves a plane crash in Virginia, but did well abroad and on DVD and is now a Cult Classic.
An even worse case was narrowly averted; the studio's ideas about the casting of Donnie included Mark Wahlberg (who was already thirty) and Vince Vaughn (who was already thirty, and didn't look eighteen when he was eighteen).