It was a film with a seriously daunting task: to predict the future of space exploration.

But together, author Arthur C. Clarke and director Stanley Kubrick created what has become one of the most revered films in cinema history — 2001: A Space Odyssey.

The film explores the origins of humankind, and our growing relationship with, and potentially dangerous reliance on, increasingly intelligent machines.

2001: A Space Odyssey turns 50 this week, so to mark the occasion, we've gathered 12 fascinating facts about the film, from its Canadian connections to the cost of the giant centrifuge to the new tech they used to make a pen float.

HAL is a Canadian

HAL wasn't really a person at all; technically he was a "heuristically programmed algorithmic computer." He was also the main antagonist in 2001: A Space Odyssey — the computer that controlled, and nearly killed, the crew of Discovery One. But there is a human connection, and a Canadian one at that: the actor who performed HAL's soft, calming voice in the feature film was none other than Winnipeg actor and Stratford Festival veteran Douglas Rain.

But HAL wasn't the film's only Canadian connection

2001: A Space Odyssey is very much an American film, but it was inspired at least in part by a Canadian National Film Board short called Universe. Director Stanley Kubrick reportedly watched as many space films as he could find, but the Canadian film — which was nominated for an Oscar in 1961 — had an especially strong impact.

"As the film unspooled, Kubrick watched the screen with rapt attention while a panorama of the galaxies swirled by, achieving the standard of dynamic visionary realism that he was looking for," remembered biographer Vincent Labrutto. "These images were not flawed by the shoddy matte work, obvious animation and poor miniatures typically found in science fiction films. Universe proved that the camera could be a telescope to the heavens. As the credits rolled, Kubrick studied the names of the magicians who created the images."

Those names included special effects artist Wally Gentleman, who went on to work on 2001, and voiceover artist Rain, who went on to play HAL. Make sure to check out the sequence starting at 5:50, because if you're a 2001 fan, it will look very familiar.

The lead actor who plays mission commander David Bowman got hired without an audition

Actor Keir Dullea, who played U.S. spaceship Discovery mission commander David Bowman, landed the part without even having to audition — and even now he's amazed. "I'd never met Kubrick before getting hired," he said in an interview earlier this month. "And looking at my previous work — The Hoodlum Priest, David and Lisa — I don't know how he got the idea from the characters I was portraying that I was right for the part. But I guess he had insights that I don't have."

But he wasn't entirely surprised. Several years earlier a palm reader at a fair had told Dullea there was a rocket ship in his future.

The floating pen scene relied on a brand new technology

Of course CGI didn't exist when 2001 was first created, so how did they get the pen to drift so smoothly in that classic floating pen scene? They used a brand new technology: double-sided tape. The special effects artists taped the pen to a large circular piece of glass, which they could then rotate and swivel to give the illusion that the pen was floating. "You can actually see [actress Heather Downham] pull it off the glass if you look carefully," remembered special effects artist Brian Johnson. "I think probably if she'd twisted it slightly it might have worked better but it worked."

The sets were as extremely detailed and intricate as they look on film

Kubrick was known to follow whims and change his mind, so he demanded sets that would allow him to move the action to unexpected areas. This meant for sets that were large, expensive and minutely detailed. "The reasons for this were twofold," said Andrew Birkin, who was in charge of tracking the special effects work, in an interview. "It gave the actors a great sense of reality, and it also allowed Stanley to change his mind. He might decide to put the camera here — or there. But it seemed like a ridiculous extravagance to many. The crew, being British and supercilious, respected him, but they thought he was completely crazy."

One of the most important scenes was a last-minute improvisation

In one of the film's essential scenes, astronauts David Bowman and Frank Poole discuss the possibility of having to disconnect HAL, but it turns out the computer can read their lips — a last-minute suggestion from one of the crew members.

"I came up with the idea of going into the pod where Bowman and Poole could discuss the various technical issues of disconnecting HAL," actor Gary Lockwood remembered in an interview. When a crew member said, "Why can't HAL read your lips?" Lockwood says that everyone "just looked at each other like, 'That's it.'"

Kubrick wanted the film to be as scientifically accurate as possible

Both author Arthur C. Clarke and Stanley Kubrick were committed to making the film as scientifically accurate as possible, even if they were projecting more than 30 years ahead. "I'm prepared to argue that all the hardware will look something like this. The spacecraft, the space suits, the space stations — all these things which are shown in great detail are very firmly based on today's technology extrapolated three decades into the future," said Clarke in a CBC interview in 1968, where he also predicted that humans would soon colonize other planets.

"I think that about the 1980s we'll be establishing the first bases on the moon, rather like those in the Antarctic. But later we'll try and make them self-contained and self-sufficient, growing their own food locally, providing oxygen and water from local lunar resources," he said. "And then, maybe around the turn of the century, we'll be doing the same thing on at least Mars and perhaps some of the other planets or satellites of the planets."

The special effects were painstaking — and expensive

The film's special effects took more than 18 months to complete and cost $6.5-million U.S. — roughly two thirds of the entire film's budget. According to the book The Making of 2001: A Space Odyssey, roughly half the film required process work, and each shot took an average of 10 laboratory steps to complete. In the end, it's estimated that 16,000 separate shots were taken to achieve 205 effects, and they included miniature models in extreme slow motion, front or rear projected film, separately photographed astronauts and pods, and a field of moving stars and planets.

One of the biggest single expenditures was the ferris wheel-shaped centrifuge that was 40 feet in diameter and could slowly rotate: it cost $750,000 to build. A closed-circuit TV system allowed Kubrick to direct from the outside, and the cameras could either be attached to a dolly that followed the actors, or to the centrifuge itself to follow the moving set.

For one scene they even had to invent a new camera

At the time there was no computer-generated effects, so everything had to be done in camera. According to visual effects supervisor Douglas Trumbull, for the psychedelic sequence at the end, when Bowman seems to pass into a different dimension, they had to invent a whole new type of camera.

"[It was] the Slit Scan, a giant machine nearly 20x30 feet. It ran for 24 hours a day, taking photographs of 15 foot-tall artworks, backlit and full of patterns and coloured gels," said Trumbull in an interview. "These were turned into controlled blurs – like if you leave a camera shutter open while shooting cars at night, you get streaks of light. A single frame of film took four minutes to produce, so the Stargate sequence took months and months."

The writer of the musical score got a raw deal

Kubrick hired composer Alex North to write the score, and he set to work starting in December 1967. North was holed up in a London apartment and was barely given any of the film to watch, but still he wrote and recorded over 40 minutes of music. At the same time, however, Kubrick found that he liked the pieces he had been using as temporary tracks — Johann Strauss II, Richard Strauss, Ligeti — and told North he might end up keeping them instead of using the original score.

Working to Kubrick's tight deadline, North ended up experiencing back spasms so severe that he had to be taken to recording sessions in an ambulance — but in the end, Kubrick gave him the boot. "I'm really sorry it all had to end this way without some discussion in connection with the music I had written," North wrote to Kubrick. Still, he wished the director well. "All the best to you on the film. ... what I saw is pretty sensation[al] ... so good luck man!!!"

At first the reviews were terrible

Many reviewers panned the film, or at least expressed bafflement. Even the New York Times reviewer wrote that it expressed "a very special sort of boring fascination" and that it looked like "a 1950s chocolcate bar."

The film, however, was an instant hit with young audiences (many of whom were watching it "while smoking funny cigarettes," quipped Dullea) and later landed Oscar nominations for direction, original screenplay and art direction, and won for special effects. Still, Kubrick — who never did win a best director Oscar — was bothered by the film's initial chilly reception. "New York was really the only hostile city," he told Playboy. "Perhaps there is a certain element of the lumpen literati that is so dogmatically atheist and materialist and earth-bound that it finds the grandeur of space and the myriad mysteries of cosmic intelligence anathema."

The film provided an early glimpse at artificial intelligence

At the time the film was made, the internet as we know it was still decades away, and the idea that computers could "think" was relegated to the realm of sci-fi. While many of Clarke's predictions didn't materialize, his vision of computing as it was portrayed in the film was eerily accurate.

"This is something which we have in the movie, this computer HAL who takes over the operation," said Clarke, speaking with CBC about 2001 and the idea of artificial intelligence, in that 1968 interview. "Many computer scientists think that we will develop, before the end of the century, machines which are intelligent by any way you care to define that word. In fact, there are some computers now that can carry on conversations with you over an electric typewriter and people just will not believe they're talking to a machine even though the conversation is limited to rather restricted areas. But many scientists think that in the next century we will have machines which are more intelligent than us, and of course this may be one of the great divides in history."