The advertising poster is a spoof of a frequently used style for movie posters. Instead of trying to communicate anything about the plot or content of the film, it just contains multiple stacked faces of the stars. On this poster the last face visible in the row is a goat's, and the billing line above their photos reads, "George Clooney, Jeff Bridges, Ewan McGregor, Kevin Spacey, and Goat." It's also a reference to the iconic drawing posters from the Soviet communist era, showing profiles of Karl Marx, Friedrich Engels and V.I. Lenin (in some eras or world regions, often completed by profiles of Joseph Stalin or Zedong Mao).
Jeff Bridges' character Bill Django is based on Army Lt. Col. James Channon, who wrote the First Earth Battalion field manual. In the mid-'70s Channon took a leave of absence (with pay) from the army to go on a fact-finding tour of the New Age Movement, before coming back and writing the First Earth Battalion manual. The movie combines two or three separate programs: the Army's Remote Viewing program (run by the army's Intelligence and Security Command), the "Jedi" program run by the Special Forces, and Channon's First Earth Battalion (which was a concept and a field manual rather than an operational unit).
George Clooney's character, Lyn Cassady, appears to be based partly on the US military's top Remote Viewer Joe McMoneagle, and RV Project Database Manager Lyn Buchanan. A scene where information on a missing general is provided by Cassady in a Remote Viewing session is likely drawn from inspiration from McMoneagle's partly successful attempt to RV kidnap US Brig. Gen. Dozier's location in Padua, Italy (1981). The scene where computer systems are destroyed, seemingly by Lyn, resulting in his initial recruitment by Gen. Hopgood, is very close to fact.
When George Clooney's character mentions the poem about the sailor and the seagull, he is talking about the poem "The Rime of the Ancient Mariner" by English poet Samuel Taylor Coleridge, which involves an albatross.
The conical First Earth Battalion solar stove looks like a smaller Sibley stove, which was also conical but used wood coals as its heat source. It was invented for the U.S. Army in the 1850s by Maj. (later Confederate Gen.) Henry Hopkins Sibley. The army discontinued its use by World War II.
When Bill and Bob are doing movement exercises on one of the buildings at PSIC, Bill trances out and falls off the building. Bob gets off the building and runs up to Bill, asking, "Are you OK?" Bill says, "I just saw Timothy Leary." Bob replies, "Timothy Leary's dead." This is a sly reference to the song "Legend of a Mind" from The Moody Blues' July 1968 LP release "In Search of the Lost Chord". The opening lines go: "Timothy Leary's dead./No, no no no/He's outside/Looking in."