The school this was filmed at (Whitaker Middle School, formerly Adams High School in Portland, OR) was torn down in 2007 due to asbestos and black mold. The school had already been shut down when the film was shot.
This film is heavily influenced by the Alan Clarke TV drama from 1989 of the same name (_"Elephant" (1989)_). Both films chronicle senseless killings and contain many long and wandering takes of its main characters.
Despite what many critics and analysts have suggested since its release, the final film was not intended to be a pseudo-documentary about the Columbine massacre. While there's no doubt that the film was inspired by the tragedy, director Gus Van Sant meant for the film to be more of a reflection on the nature of violence and the effects of indifference. There's also a rumor that Van Sant's original intent was to make a TV film based on factual accounts of Columbine, but this rumor has remained unfounded. The film's minimalist approach, improvisational style and use of non-actors has helped to fuel these rumors over the years.
The trivia items below may give away important plot points.
Towards the end of the film, Alex drinks from a random glass in the abandoned cafeteria. This is a nod to an image from the CCTV surveillance footage from the actual Columbine Highschool massacre, where Eric Harris can be seen drinking from a glass found on a lunch table.
Gus Van Sant borrowed the title from Alan Clarke's film of the same name, and thought that it referred to the Chinese proverb about five blind men who were each led to a different part of an elephant. Each man thinks that it is a different thing. What Clarke's title actually referred to was the idea of the "elephant in the room", where something is so obvious that to miss it would be the equivalent of not seeing a huge elephant in an ordinary room, yet is still not recognized out of either stupidity or willful ignorance. In this film, the "elephant in the room" is the homicidal rage of Alex and Eric, which leaves them free to precipitate the last-scene massacre at their school.
At one point Alex and Eric watch a documentary about Hitler on TV. The Columbine High School massacre, upon which this film is based, occurred on April 20th 1999, the 110th anniversary of the birth of Adolf Hitler.