Goofs

Several times during the first half hour of the movie, O'Niel's uniform name tag changes spelling from "O'Niel" to "O'Neil" and back again.

(at around 57 mins) When O'Niel talks to Sheppard in the latter's office, the distance between Sheppard and the Io model varies from shot to shot - most obviously in different shots that are taken from almost exactly the same angle.

When Spota is shown walking through the locker room, he passes behind a man wearing a red hat as he opens his locker to change before continuing further down the center aisle. A few seconds later, Spota is shown passing behind the exact same man (now shirtless and with no hat) a second time. While it's possible that Spota doubled back, it is unlikely, because he is shown entering both shots from the same direction. If he had doubled back, he would have been coming from the opposite direction in order to pass the man the second time.

(at around 1h 20 mins) The shuttle carrying the two hit men arrives 42 minutes early on its 70-hour trip from the space station. If the shuttle gave accurate information on its course and speed, it would always arrive on time otherwise Io would be in the wrong position as it moves at 17.3 km per second due to its low orbit around Jupiter. The only way to arrive "early" would be to give Io incorrect course and speed information. Considering that there are company-hired assassins on board, the latter is a possible bit of subterfuge on the company's part.

(at around 1h 35 mins) The terrestrial atmosphere of the studio is evident, even though the exterior scenes take place in the near-vacuum of Io. When O'Niel drops the panel atop the greenhouse, it flutters away from him instead of falling straight down. The gunman shoots at the panel through the greenhouse window, breaking it, and the resulting explosive decompression causes a billowing cloud of gas and debris. Nothing "billows" in a vacuum; the surrounding air allows that, so the gas and debris should have sprayed away from the greenhouse in more or less straight lines.

Communication between Io and a faraway space station seems to experience no time delay between responses.

Io, the moon of Jupiter where the film is set, is the most geologically active object in the solar system. It has hundreds of active volcanoes that constantly change the surface of the moon, and the moon is also within Jupiter's radiation belt which emits an intense amount of ionizing radiation that would be lethal for humans. The volcanic activity of the moon causes massive plumes of sulfur and sulfur-dioxide to shoot up as high as 300 miles above it's surface. These features would make it an impossible choice for a mining colony. Filmmaker Peter Hyams would go on to depict Io as the hostile moon it really is in his next movie: 2010: The Year We Make Contact (1984).

In the exterior scenes showing Io's mining buildings with Jupiter and the stars in the background, the stars are blinking. Such blinking is caused by viewing the stars through an atmosphere, as on Earth. But Io has virtually no atmosphere - therefore, the stars should have been shining steadily.

It was more of a pulse than a blink. For the purposes of the movie, the immense gravitational field of Jupiter may have bent the light from the stars.

(at around 59 mins) When O'Niel finds the corpse in the zero-G cell, blood is shown dripping upwards. In real zero gravity, the blood would be propelled in whichever direction it was forced out of the body. With a corpse, it would simply stay in the body.

It was propelled from a pinhole by the air pressure inside in the suit.

(at around 37 mins) When O'Niel draws blood from Sagan's neck, the blood is a clear red when it should be opaque.

It's not blood. All the blood has coagulated. That is serum, lymph juice or such.

Bodies do not explode when exposed to a vacuum, a change of only one atmosphere of pressure to zero.

The inside of the helmets is lined with LED-like, multiple small lights. These would not provide any illumination, except for the inside of the helmet (the same way the interior light of a car won't help you see what's outside) . In fact, they would actively hinder or harm the vision of the person who wears the suit.

(at around 2 mins) Io is the first moon of Jupiter not the third. Considering the multiple typo and grammar mistakes in this expository part of the film, distance may have been confused with size. Io is the third largest moon of Jupiter.

(at around 1h 40 mins) While fighting with Ballard out in space, O'Niel grabs his foot to pull him off of a ledge. When he does, you can see his arm and hand inside his glove, showing his spacesuit to be fake.

(at around 34 mins) The grips on the "spacesavers" in Dr. Lazarus' office make absolutely no sense from an engineering point of view. They are far too big for what they have to achieve and the complicated hinging mechanism serves no purpose. Moreover, the joints move even at the lightest touch from O'Niel, revealing them as prop grips not even in the slightest as heavy as they look.

In the opening scenes in the mining levels, human voices are heard through the radio links, but ambient industrial noise is heard "in the clear". In a vacuum there would be no such noise. If the noise were heard from the miners' perspective (as was the radio chatter) it would have been low frequency noise from mechanical contact with the ground and manual equipment only.

As of the start of the film, workers have been freaking out for about six months at the rate of at least once per week, but when Tarlow starts to yell about imagined spiders attacking him, none of his coworkers appear to have any concern about him acting crazy until he slices his suit open.