Stupidity: When the trolls are trapped in Chef's cage, Smidge is small enough to slip through the bars and could've easily escaped.
Stupidity: When Bishop is first holding the gun on Gina in the cabin, he stands close enough for her to grab the gun and try to get it off him. A man of his experience would never make that mistake, it's one of the basic rules of controlling someone at gun point: Stand more than an arm's length away.
Stupidity: The bodyguard takes Michael's pistol from him and later shoots the pistol near Michael's ear, deafening him, then beats him a bit and leaves him on the ground. As the bodyguard is walking away he gives Michael his sidearm back by ejecting the magazine and tossing the gun on Michael's body. He however didn't eject the bullet in the chamber. Michael's gun, a Sig Sauer, doesn't have a magazine disconnect which prevents a gun from firing with a magazine removed. This was a safety feature for police. (01:33:00 - 01:37:00)
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: Since the main people could not delete, or even change their own Facebook accounts; why not contact Facebook support in order for the company to do it for them?
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: Given Enchantress' power, why not just try to cure Dr June Moone, so she can't threaten the world? That's what the government should've done.
Suggested correction: We're talking about Amanda Waller who had no issues murdering innocent government employees that were accidentally exposed to her top-secret Suicide Squad program they weren't cleared for (versus making them sign an NDA not to talk about it as in a real-life accidental exposure to uncleared employees). Waller just took the easier option which was to threaten to kill Enchantress if she didn't obey versus spending countless dollars (and exposing more people to Waller's program) trying to cure her.
Stupidity: Why would they drive all the way to Marylebone Railway Station in central London when Southbury Road station is only a thirty-second drive away?
Stupidity: Long after the Marine Life Institute has closed for the night, the recording of Sigourney Weaver welcoming visitors is still playing.
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: 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.
Stupidity: Bridget car keys are lying on the shelves (again) after she has left her bags at the ATM. I suppose they could have taken her car after all when she and Mark try to think of a way to get to the hospital.
Stupidity: Why does a safe house have a skylight? It is a secure building with hardened doors but a window in the roof?
Stupidity: Jake uses several Loops and travels all over the world in order to get back on the boat at the end of the film. This was completely unnecessary as only the final Loop in 1942, which was available to him in 2016, was the one he needed to enter despite the fact that its nature should have prevented him from reaching 1943 anyway.
Stupidity: The Joneses forget to change their New York license plates to Georgia ones as part of their cover.
Stupidity: The protagonists need to know what Pope is planning with his drug shipments, in secret. So they sneak under a false name into Pope's party and... the policewoman goes dancing with Pope, who knows her and that she is a police officer! Good that nobody asks her anything - she'd have no way to explain her presence! At no point it is even hinted that he was just about to go upstairs, why would he, after all, with all those guests? And their secret mission continues with the alarm being triggered and Ice Cube KTFOing guards. Some stealthy mission, and they are even captured at the end! And even after all these epic fails, they just assume that Pope is not going to change anything about the shipment details. And to make all of this even worse, they know about the port commissioner situation, they talk about it and how necessary it is for Pope to control the commissioner, but don't take half a second to mention his name, which is all it takes for AJ later in the movie to 'remember' that he's been bribed.