Factual error: Bill Kempt rigs the sapphire asteroid with rocket motors to divert it toward the Moon. The motors are old and cranky, and to ensure that they fire on time he must, at some risk, lash himself to the rock and manually start the ignition. Upon lighting the engines he has several seconds to cut himself free, but in the scene he's shown swinging weightlessly as he snips the cable. If the asteroid is accelerating, he ought not to be weightless, but rather should be hanging behind the rock on his tether.
Factual error: In nearly every scene depicting someone or something in weightlessness (zero gravity), objects tend to start moving randomly without any initial propulsive force or, when already in motion, to been seen to randomly change direction of movement with no outside force acting upon them. Both of these are impossible in a true zero-G environment.
Factual error: If 2 spacecraft are travelling towards each other's planets, at the same speed, it would still take 6 weeks to get to each other's planet. They kept saying they must've turned back cause only 3 weeks elapsed.
Suggested correction: Where do you get it would take 6 weeks to travel to the other planet? Throughout the film they're constantly saying it's a 3-week trip to the planet and a 3-week trip back home, for a 6-week round trip.