Character mistake: During the debrief meeting with the generals, Roy states the Lima Project was "some 29 years ago" and "the ship disappeared approximately 16 years into the mission." A few minutes later, Roy narrates "I was 16 when he left, 29 when he disappeared." This of course is only 13 years into the mission. (00:11:27 - 00:15:03)
Character mistake: Brad Pitt ends his message to his dad by saying "over and out", which is often used in movies but not how radio communication works. "Over" signifies the end of your current speech, "out" means you're done with the conversation. You use one or the other, not both.
Character mistake: Brad Pitt has control jets on his space suit - he uses them to accelerate him back towards his ship at the end, but somehow doesn't think to turn himself around and use them to slow down, hence slamming into the ship at great speed. Given the skill he demonstrates every other time in the movie, this only seems to happen for the sake of a dramatic arrival.
Suggested correction: It is not unfeasible that he used the RPS fuel to accelerate and had none left, since he already wasted a certain amount after his father pulled him away from Lima station.
In space you can't just swing around and change directions because there is no friction or gravity. He would have to have a jet that shoots forward (a retrorocket) or he would have to turn using the jets which would make him go in the opposite direction, not slow him down. From what I saw, there was no retrorocket on his pack.
There were retrorockets in his father's suite, he was flying in space using them. Why there was no such rockets in Roy's suite, wasn't it exactly the same? Helmets were identical, and other details too. He could slow him down.
There are no 'rockets' or 'retro rockets' on an EVA space suit, just thrusters that used in combination and with direction of the nozzles, can make it move any way they want, including turning and yes, slowing down. It's just Newton's Laws.
Character mistake: When Cepheus stops accelerating (which it would not have done until it turned to decelerate) crew plays in zero G's like amateurs who had never been in space. They were described as professionals with a lot of experience. They would never have risked fluid in the electronics by doing what they did.
Suggested correction: In fairness, they were on drugs (mood stabilisers) at the time. This might have affected their judgement.