Factual error: How would the creature be able to re-enter the ship by climbing into the reactor piping? The reactor fuel system is not open to the living space of the International Space Station.
Factual error: After Dr. Derry's hand is crushed by Calvin, it dangles and flops every time it is seen so that the audience can see that the bones are severely broken. However, in zero-g, the hand would float rather than swing limply.
Factual error: When the probe from Mars crashes into the space station, it's probably doing 17,000 mph or even more, which would completely demolish whatever is in its path. It's not believable that some 'arm' could stop it.
Factual error: The way the life form moves through the ship is silly. In weightless conditions, you can only move by pushing yourself off a wall or other stationary object. This creature seems to move throughout the ship by flailing its tentacles, which is nonsense.
Revealing mistake: Throughout the film, the characters can be seen to impossibly pivot on the rigging suspending them in the air in a manner inconsistent with zero-g as they move through the space station.
