Stanley Kubrick cut 19 minutes from the film's original 158-minute running time after its New York premiere, mostly to speed up the pacing.
Stanley Kubrick had several tons of sand imported, washed, and painted for the moon surface scenes.
Stanley Kubrick initially approached Arthur C. Clarke by saying that he wanted to make "the proverbial good science-fiction movie". Clarke suggested that his story "The Sentinel" (1948) about finding an alien artifact on the moon, would provide a suitable premise. Clarke had written it for a BBC competition, but it didn't even make the shortlist. The movie's opening scene has elements in common with Clarke's story "Encounter at Dawn," and the ending is arguably related to his beloved novel "Childhood's End." The screenplay was written primarily by Kubrick and the novel primarily by Clarke, each working simultaneously and also providing feedback to the other. As the story went through many revisions, changes in the novel were taken over into the screenplay and vice versa. The official records say that the screenplay was written in 58 days (13 October 1965-9 December 1965). Shooting began with the "Monolith on the Moon" scene on 29 December 1965. It was undecided whether film or novel would be released first; in the end it was the film. Kubrick was to have been credited as second author of the novel, but in the end was not. It is believed that Kubrick deliberately withheld his approval of the novel as to not hurt the release of the film.
Stanley Kubrick kept the costume of Moonwatcher.
Stanley Kubrick previewed 2001: A Space Odyssey for critics, but quickly regretted doing so. Among the mostly indifferent and unfavorable reviews, as noted in the Documentary, 2001: The Making of a Myth were: "Somewhere between hypnotic and immensely boring"-The New York Times, "A monumentally unimaginative movie"-Harpers, "Space Odyssey fails most gloriously"-Newsday, and "Big, Beautiful but plodding scifi epic. Superb photography major asset to confusing, long-unfolding plot."-Variety
Stanley Kubrick was initially forced by MGM to have Alex North (who had written the score for Kubrick's Spartacus) compose an original score for the 2001. Kubrick, however, always intended to use classical music for the film. He allowed North to score the first half of the film before informing him they planned to use only sound effects for the second half. It wasn't until he was watching the film at its premier in New York that North discovered that his music had not been. North later reused themes composed for 2001 in the films The Shoes of the Fisherman, Shanks, and Dragonslayer. North's original score was unheard for 25 years until composer Jerry Goldsmith re-recorded it for Varese Sarabande in 1993. In 2007, however, Intrada, working with Alex North's estate, released North's personal copies of the 1968 recording sessions on CD.
Stanley Kubrick was very well read. It is rumored that the image of the star-child came to him from the "Spirit of the Earth" in Percy Bysshe Shelley's "Prometheus Unbound": "Within the orb itself, Pillowed upon its alabaster arms, Like to a child o'erwearied with sweet toil, On its own folded wings and wavy hair The Spirit of the Earth is laid asleep..."
Stanley Kubrick worked for several months with effects technicians to come up with a convincing effect for the floating pen in the shuttle sequence. After trying many different techniques, without success, Kubrick decided to simply use a pen that was taped to a sheet of glass and suspended in front of the camera. In fact, the shuttle attendant can be seen to "pull" the pen off the glass when she takes hold of it.
Stanley Kubrick: [classic/parlor games] Even in outer space, mankind enjoys a classic game of chess.
Stanley Kubrick: [faces] Dave Bowman going through the Star Gate.
Stanley Kubrick: [zoom] as Dr. Floyd reads the zero-g toilet instructions.
Arthur C. Clarke and Stanley Kubrick disagreed on what HAL's birthday should be. Kubrick wanted HAL to be about the age of a child, so his death would have more emotional impact. Clarke insisted such an old computer would not be used for an important mission. In the book, HAL's age was four years (12 January 1997), while in the movie it was nine years (12 January 1992). This disagreement resurfaced nearly thirty years later when film critic Roger Ebert held a birthday party for HAL 9000 by screening 2001 in Urbana, Illinois in 1997, the date and place of HAL's birth in the novel (Ebert was also born in Urbana). Clarke and Kubrick were both invited. Clarke accepted his invitation and made an appearance at the festivities via satellite, but Kubrick declined, stating that they missed HAL's birthday in 1992. Another inconsistency in this scene is the name of HAL's first instructor. It is Mr. Langley in this movie but is Dr. Chandra in all other books and movies in this series. Since HAL is saying all this while being shut down, this could be interpreted as a result of memory failure.
Frank Miller, who plays the mission control voice, was a member of the US Air Force in real life, and a real mission controller. He was hired because his voice was the most authentic the producers could find for the role. Inexperienced and nervous, he could not keep from tapping his foot during recording sessions, and the tapping sound repeatedly came through on the audio tracks; Stanley Kubrick folded up a towel, put it under Miller's feet, and told him to tap to his heart's content.
Marvin Minsky, one of the pioneers of neural networks who was also an adviser to the filmmakers, almost got killed by a falling wrench on the set.
According to Stanley Kubrick biographer John Baxter, Kubrick decided to use the Sinar Front Projection system for the desert backdrops during the animal/ape scenes. This method was selected because rear projection of the desert scenes would have proved too murky for Super Panavision. The use of the Sinar system explains why in the scene where the leopard is sitting next to the dead zebra (in reality a painted dead horse) the leopard's eyes glow a bright color. The Sinar system used glass transparencies as backdrops; however, the projectors necessary for this system were so hot that a draft or a breath could crack the glass. As a result, crew members were required to wear face masks, which started a long-persistent rumor that Kubrick had a paranoia of catching infections.
According to Arthur C. Clarke, Stanley Kubrick wanted to get an insurance policy from Lloyd's of London to protect himself against losses in the event that extraterrestrial intelligence were discovered before the movie was released. Lloyd's refused. Carl Sagan commented, "In the mid-1960s, there was no search being performed for extraterrestrial intelligence, and the chances of accidentally stumbling on extraterrestrial intelligence in a few years' period was extremely small. Lloyd's of London missed a good bet."
According to Douglas Trumbull, the total footage shot was some 200 times the final length of the film.
After seeing a documentary called To the Moon and Beyond (not listed on IMDb) at the 1964 New York World's Fair, Stanley Kubrick hired one of its special effects technicians, Douglas Trumbull, to work on this film. Trumbull developed a process called Slitscan photography to create the wild, kaleidoscopic images Bowman experiences going through the Stargate. It involved moving the camera rapidly past different pieces of lighted artwork, with the camera shutter held open to allow for a streaking effect. The overall effect gave the audience the sense of plunging into the infinite. Trunbull was later hired by ABC to produce the famous opening sequence for the ABC "Movie of the Week" using the same slitscan technique used for 2001.