Stupidity: You'd think that Jezzie would have been a little smarter as a secret service agent. You know, like once they acquire Megan, to delete all the incriminating evidence sitting back on an unattended computer. Aside from the fact she also used quite a stupid password, a single password isn't very secure at all. And then the content, displayed instantly when you get in, might as well say things like "hey look, we know what the kidnapper looks like" and "wow, here's the boat he's in too" and "wow, a cabin for sale. Why don't we go hang out there with all the evidence." Come on....they might as well have left a trail of breadcrumbs, because they sure were asking to get caught.
Stupidity: If Jordan was inside the cake and the cake was right there in the room when the takeover began how did the bad guys forget she was still inside?
Stupidity: When the Keymaker is closing the door to the room that leads to the Source, he stands in the doorway resulting in the multiple Agent Smiths gunning him down. He could have easily closed the door without standing in the doorway and consequently would have lived.
Suggested correction: Who says the door was bullet proof and the Keymaker couldn't have been shot through the door?
The point of the stupidity is that he shouldn't have been in the doorway at all, even if the door wasn't bulletproof, there was no need for him to even stand behind the closed door. He could have pushed the door closed from the side.
It seems to be a heavy door, he simply couldn't close it with just his arm, thus he had to move his body forwards in order to close it. In that brief moment he got shot before the door closed. He could have for example kicked the door shut but he simply didn't think of that at that moment, also not knowing the Smiths were about to fire a volley of bullets at them.
Stupidity: When Christine is told that to remove the curse, all she had to do was give an envelope with the button inside to somebody else and that individual would go to hell. She decides to go to the cemetery where Ganush is buried and places an envelope into her mouth. Had Christine actually bothered to check inside the envelope first to see if the button was inside, she would never have gone to hell.
Stupidity: When Colonel Hardy is about to crash the ship he's flying into a building, Faora sees it and she has more then enough time to leave the ship and get to safety, but she does nothing and just stands there.
Stupidity: The bad guys should have just shot Paul and his backup during the standoff rather than risking another impediment.
Stupidity: In the first action scene where James Franco's body becomes mortally engulfed in flames in his cryopod, when they are using the jaws-of-life-hatch-removing tool to manually free him, there are two very strong men struggling with all their might to pull down on the levers to pop the lid off. A) If you watch closely, one of the guys is only using one hand to pull down on the lever. Hardly a serious effort to crank the thing open. B) Meanwhile, there are three other men present who, rather than jumping in with the other two guys trying desperately to pull those levers down, are instead ridiculously engaged in holding Franco's hysterical girlfriend back from the now-flaming pod. (00:10:00)
Stupidity: When Ruth catches Chuck fishing for turds in their toilet, he yells at her and asks for privacy and then slams the bathroom door shut. He should have closed the bathroom door in the first place if he didn't want anybody to see what he was doing. It's not like anybody would think he was weird for going into the bathroom and immediately closing the door.
Stupidity: Bori Khan is a skilled archer and a man without honor. He's not fighting fair, and cares just to win, as established and explicitly said. He shoots an arrow at Mulan, the Witch gets in the arrow's way sacrificing herself to protect her...and for no reason whatsoever he does not shoot anymore, giving the chance for the two girls to share their very special dramatic moment together, but creating a colossal plot contrivance. It is a know movie cliche for the fight to 'pause' around the main character, but here we have a sniper who desists completely (he won't shoot anymore) for absolutely no reason. (01:29:00)
Stupidity: Shriek is being taken to a new facility for superbeings, after a medical exam established that her sonic powers that she has been using since she was a kid are too strong to keep her at the correction house. So "naturally" for this transport she is not gagged, sedated, not even bound, and there's just one guy with her, not even wearing earplugs. It couldn't possibly be any more comically unsafe.
Stupidity: At the beginning, young Indy knocks out the driver of the car, pulls him out, and just leaves him on the ground by the car while entering the car. Neither the knockout nor the unconscious driver lying around are noticed by any Germans in the vicinity. Not even by the soldier who opens the car door and the officer who gets into the car, both of whom immediately appear after Indy has gotten into the car. (00:06:00)
Stupidity: After stealing the taxi, Cassandra removes the license plate, and yet the taxi's identification number is located in bold plain sight on the doors and roof light.
Stupidity: Why would Gabriel have an item as valuable as the Poison Pill dangling from his neck (and therefore susceptible to falling off or being snatched by Ethan) during the airplane sequence rather than have put it in a secure location like a closed pocket before takeoff?
Stupidity: Granted, Coffee is suffering from "high-pressure nervous syndrome," but if you're a Navy SEAL, wouldn't you notice whether or not your pistol has a magazine in it? Monk pulls the clip out of his jacket and starts knocking rounds out of it for the rig crew's benefit; the same dramatic effect could have been achieved with a handful of cartridges he could let slip through his fingers. You could argue that Monk didn't have enough time to unload the gun and replace the magazine, but in that case, I think the scene where Monk briefly had the gun should have been a bit longer. (Even had the empty magazine been IN the gun, Coffee still might notice the difference in weight, but that would be easier to suspend your disbelief for.) (01:43:53)
Stupidity: Jill wasn't thinking too clearly when she plans her story. She only wiped the fingerprints off the gun but they would be all over the tape on Trevor's body. Then she wipes off the knife yet touches it again to slide it across the floor. She was thinking that Trevor and Charlie were going to be thought of as the killers but their fingerprints weren't on either of the weapons.
Stupidity: During one of the test drives, the hook that Hiccup uses to fasten himself to Toothless gets bent, so he takes Toothless to the blacksmith to cut the line. There are two ways he could have easily avoided this: He could just unhook the saddle, take that to the blacksmith and cut himself loose, or he could just untie the leather strap. What he does here is needlessly risky and just there for his awkward conversation with Astrid.
Stupidity: When Gaz tries to steal a jacket and Dave, who works as security, catches him in quite a dramatic manner they are seen by other employees. Dave lets Gaz go because he is a friend. But the next day both stroll together through the shop as if nothing had happened, with no enquiries or follow-up from the other employees. (00:59:30)
Stupidity: Reliant's prefix code is 16309. This code prevents an enemy ship from ordering a friendly ship to lower its shields or something similar. Five digits with no symbols. We know that symbols and letters aren't used since Spock uses a 10 digit set of switches to input the code. This is ludicrous. In 2016, a high powered server could crack a 6 digit password in approximately 0.0224 seconds (at 100 billion guesses/second). Any starship computer would have to far more processing power then a 2016 server. The prefix code protecting a starship from cyber attack would have to be insanely complex in order to be useful.
Suggested correction: Keep in mind the era that this movie was made in. This movie was made before PCs really existed. Computers at this time were typically huge devices or box like containers. Their data storage capacity was minuscule and there certainly wasn't any form of AI logic programs built to "hack" passwords. I know this movie is about space and set in the future but there's a lot of stuff in Star Trek movies that based on our technology or development currently, we would expect something bigger, smarter, etc. We still have problems today with people using archaic password structures like 1.2.3.4. or actually using the word password for/in their password. Back in '81-'82, I'm sure that most people would not have thought about codes being hacked. This is not to mention that in many movies, which I don't know if there is a specific reason for using 16309, codes, passwords, numbers for addresses/apt#/room#/etc and other info frequently come about as tribute, honoring, or coming from something in the lives of a film's director/producer/actor/etc! So sure with today's technology, which could have been accomplished more than 10 years ago as well, using a single string of numbers as security measures for anything is foolish and can be hack by a self running password-like cracker program... But they made this "code" back in the very early 80s when computer hacking was barely unconscionable (MAYBE) so unless these #s were a tribute or to honor something, I'm pretty sure no one was even thinking of hacking back then... We all aware of today... all about the hacking threats and YET we still have people using 1.2.3.4., the word password, or other horrible predictable password choices that can easily be broken by a password cracking program... And we know that there's a huge hacking threat requiring strong security measures but don't do so while back then, there was little awareness of the threats of hacking much less the concept of hacking altogether.
OR... in this future they have limited the number of password attempts to one a day and the ship automatically goes to red alert after a failed attempt until the right code is entered. That way it would take 7,327 years or so to try all the codes with the crew on notice and plenty of time to address the threat.
Stupidity: When Greg volunteers to watch the security monitors to see if the creatures can affect people through a screen, no-one even thinks to remain in the room with him to cover up the monitors with a blanket, towel or something similar in case the creatures' power can be transmitted that way. They tied him to a chair to reduce his chances of committing suicide, so they certainly thought there was a possibility that he would be in danger.