Stupidity: When the army base gets overrun the girl jumps on a soldier and starts biting his neck. The woman soldier that's with him aims her gun at them but doesn't shoot, knowing full well there's no hope for the man. There is utter carnage going on all around them and instead she tries to help him and gets attacked in the same way. This could be a plot hole as well as the girl in question is the one that holds the key to survival.
Stupidity: The chef/cook of the house has his rifle, and he knows Morgan lost control and pretty much killed everybody on the premises. He comes face to face with her, but he lowers his rifle instead of taking the subject (Morgan) out with a shot. There is no logic here but to only pro-long the film. There's no reasoning with a scientifically created subject which is killing everybody it comes into contact with. (01:09:00)
Stupidity: When Doss buried the wounded soldier, leaving one eye out made no sense. It did nothing to help him. All it did was make it easier for the Japanese to spot him. It would've made sense to leave his nose and/or mouth out, so he could breathe. He did not need to see.
Suggested correction: A person who is unable to see is more likely to panic. When Doss buried the wounded Marine, he asked him to take a deep breath and trust him. By leaving one eye open, it allowed him to see the gravity of the situation as IJA soldiers walked by and maintain eye contact with Doss who hid under a dead Marine. After the suspicious IJA soldier bayoneted the body over Doss, he looked directly at where the wounded man was buried and kept walking. It was a crude method, but it likely saved them both.
Stupidity: Gus is a blatant example of Deus Ex Machina. 1: The % of his pod malfuntion was too low. They mention multiple times how low the chances of a pod malfunction are (Jim's is the first in history), and then it happens twice? Jim's med-scanned him but Gus' didn't (?) so he had 610 things wrong with him. So he woke up dying 2: Gus' existence has only one objective: to give Jim the armband. 3: Before anything else can happen with Gus, he dies conveniently. Gus' existence had no other reason. We didn't care about him emotionally. He didn't advance the plot. He provided no new info or answers to questions. (failure cascade is easily discernible by Jim once he has access to the bridge) It would have been easier to just let Jim find an armband/access another way. DXM: holder of the macguffin magically appears (pod failure) delivers the macguffin (armband + code) goes away (dies without explanation) it's downright shameful.
Suggested correction: This is all your opinion of a plotline - admittedly, an utterly lame one - not a film mistake. Film criticism and error spotting are two different things.
In addition, the statistics about pod malfunctions obviously referred to spontaneous malfunctions, which had never happened. These malfunctions in the movie, however, were not spontaneous – they were caused by catastrophic failure of the ship itself due to an asteroid hit.
Stupidity: When Sook-Hee walks into Hideko's bedroom before the two of them have sex, she slides the door open when going into the room and never closes it behind her. Once the two of them are in bed together and when they have sex, the door is left the way it is and never closed. Considering a sexual relationship between the two would have been completely forbidden, and, if they were caught, would likely ruin the plot to steal the inheritance money, it seems very foolish of them to ignore the open door, especially taking into account there are other people inside the mansion who could walk by at any moment. (00:41:30)
Stupidity: During the movie, the bad guys keep the main character alive and free to roam the facility at will (even if they made him sign an incriminating form at the very beginning stating he's an inmate) doing absolutely nothing to restrict his freedom till the very end - he even retains personal effects like his broken Rolex and lighter, his wallet full of cash! He breaks into every forbidden area, picks up fights, damages property, escapes multiple times and 'corrupts' the person the whole facility is built for. He is worth absolutely nothing to them and has nobody waiting for him or that will look for him.