Stupidity: How on earth did those helicopter gunship pilots survive a tour of duty in Vietnam? They are too stupid to tie their own shoelaces. They have encountered a thirty metre tall ape which is intent on killing the lot of them by grabbing their helicopters and smashing them to the ground, so they have two clear choices - a) use their heavy, mounted machine guns or the grenade launchers fitted to the assault rifles carried by the troops on board to shoot the thirty metre tall ape to ribbons from a couple of hundred metres away, well out of its reach or b) fly straight up to it and present an easy target, allowing it to kill the lot of them by grabbing their helicopters and smashing them to the ground. Every single one of them ticks box b). Idiots.
Stupidity: The Death Star comes equipped with a powerful tractor beam capable of capturing a ship the size and agility of the Millennium Falcon. Why don't they use it against the rebel fighters attacking them at the end of the film? Okay, Obi-Wan Kenobi turned it off earlier but I find it hard to believe that someone who has never before visited the largest, most complex space station in the Universe and who was previously unaware of its very existence can disable a fundamental security system but the people who designed, built and run the whole thing can't work out how to switch it back on. They should have no problems with this, considering the fact that Obi-Wan didn't damage it.
PEDAUNTSuggested correction: Obi Wan disrupted the battle at a critical time causing much confusion. We could chalk this oversight up to "Fog of War" - that in the heat of battle it's normal for commanders to overlook obvious things and seem to act stupidly. It would also be reasonable to assume that the fighters were too close for the tractor beam emitter to target them.
Suggested correction: The Falcon was travelling towards the Death Star when it was caught in the tractor beam. The tractor beam was properly turned back on by the time it travelled to Yavin. The rebel fighters are too small and quick to be held in a tractor beam and there are so many of them so it would be near impossible to trap enough to make a difference.
Stupidity: After Josh runs away from home after being turned into an adult, nothing seems to be done about his "disappearance." The only indication that he is missing is his picture on the back of a milk carton. There's no flyers about him missing. No mention of his disappearance in any newspapers or TV news about his mom saying that he's been "abducted" by a stranger. Even when Josh writes a letter home, he uses the actual address of where he's staying, but no cops turn up at his door after his mom receives the letter.
Stupidity: The Engineer and Fireman of the Polar Express train crew should have known better than to not bend back the the metallic prongs of the cotter pin, which would have prevented the cotter pin from coming loose and causing all those problems in the driving of the train.
Scott215Suggested correction: As you yourself stated, the whole thing is likely a dream, where "normal" reality doesn't apply. In the "real world", the train would never be able to do any of the things that it does in the film.
wizard_of_gore
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: 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.
Friso94
Stupidity: The commando mission to save Chewbacca starts gunning down a few Stormtroopers in the hangar. The heroes then go on leaving the troopers lying down on the floor in front of the ship, in plain view. They don't hide them nor ask the droids (who have enough strength and tools to pull them in) to, in fact they tell them to stay put. No wonder they are found out later (after a ridiculously long amount of time).
SammoSuggested correction: Hiding the bodies would have been a waste of time, anyone who came to the hangar would immediately notice that the guards stationed there were missing and there was now a strange ship parked there.
BaconIsMyBFF
Stupidity: It's stated that Imhotep will fear cats until he has fully regenerated and two different scenes show him fleeing in terror at the sight of a cat. Despite this, none of the characters that Imhotep is trying to kill that are fully aware of his weakness even think to have a cat with them at all times.
Phaneron
Stupidity: Steve Trevor is the leader of a group of Allied spies, and they are traveling with a gorgeous woman who has shown to have amazing fighting skills and super powers, but they allow a group photo to be taken with Diana in her armor. They don't know who is taking the photograph nor what they intend to do with it. Their photograph circulating through a news publication or passed on to an enemy's intelligence service could compromise himself and the rest of his team, and they would absolutely know that. Undercover agents do not pose for photographs.
wizard_of_goreSuggested correction: The photographer is not a reporter, he is one of the villagers. The photo was not taken to be circulated through print media, it was taken by the villagers to commemorate the day they were liberated. There only appears to be one copy of the photograph (which Bruce Wayne finds and sends to Diana), so the likelihood of it falling into the German's hands is incredibly slim.
BaconIsMyBFF
Stupidity: After the Slick devours Laverne, Randy jumps into the water and swims for shore with the Slick following. Even though Randy made it to shore, he stops and turns to confront the Slick, screaming that he beat it. When Randy turns around, the Slick immediately envelopes him. If Randy had just got up and started running instead of facing the Slick, he would have lived.
Suggested correction: This is a deliberate movie making technique to make the audience think the character has escaped but at the last second a surprise is thrown in. It's the same as hanging over the body of the killer. It doesn't come under stupidity.
The_IcemanSuggested correction: Randy's decision isn't what constitutes a "stupidity" mistake. Stupidity mistakes are minor plot holes, which means characters can act stupid. Plus, when Randy gets to shore he's worn out so he tries to catch his breath. He then says he's won because he under estimated the Slick's ability to get him (which would fall under the category of "celebrating too early").
Bishop73
Stupidity: The eco-terrorists leave the Orca completely unattended allowing Madison to take it without anyone realizing until she is long gone. In addition, they don't post any guards at the exit of the bunker and Madison simply walks away without anyone noticing her at all.
BaconIsMyBFFSuggested correction: They leave the Orca in their empty command room within a bunker filled with loyal men. There is no way anyone could have broken in and stolen it. Madison had the advantage of already being in the bunker and even then had to navigate through the air ducts in order to steal the Orca and escape. They wouldn't have armed men visible immediately outside because they didn't want anyone to notice that they were there.
Stupidity: When Han tells Drydon Vos that he and Tobias will steal unrefined coaxium from the mines on Kessel, Vos initially says no, as Crimson Dawn's relationship with the Empire would be at risk. Han then explains that the Empire wouldn't know they were working for Crimson Dawn. Vos then agrees but insists his top lieutenant Qi'ra accompany them, even though she is a known associate of Crimson Dawn and literally has their symbol branded on her wrist.
AbbyJay
Stupidity: Dr. Jekyll must take an injection to keep himself from turning into the murderous Mr. Hyde. Hyde obviously doesn't want Jekyll to take the injections because he wants to remain in control of the body. The time between when he begins to feel himself turn into Hyde and when he has fully transformed is ridiculously brief. Why then does he keep the syringe locked in a box in his desk rather than on his person at all times?
BaconIsMyBFF
Stupidity: Al is supposed to be a super serious toy collector and seller, but he handles valuable toys without cleaning the cheese puff dust off his hands.
wizard_of_goreSuggested correction: It's also established someone is coming over to clean said toys, dust included, and when he does the handling, he's just been sharply awakened by the TV therefore is off-kilter.
dizzyd
Stupidity: When Superman gets to the bridge after the truck falls off, he asks the firemen if there's anything he can do. They responds that there's really nothing as he got there too late. How about asking him if he could get the truck out of the water. That would have been a help.
Gavin Jackson
Stupidity: As Powell was standing at the completely wrong "eye" in the temple to begin with, all Lara had to do was say nothing of his mistake, he'd never had got the first piece of the triangle to begin with, world safe for another 5000 years.
Stupidity: In the scene when the cook is torched, why didn't he just jump out of the longboat into the water? Why get burned?
Suggested correction: It would be pointless. If he ran away, Blackbeard would just come after him and make him suffer greatly. At least the fire is quicker than torture or being zombified.
Stupidity: When Spider-Man confronts Aleksei Sytsevich in the truck while he's plowing through the busy streets of New York, he sits there and starts cracking jokes instead of immediately trying to stop the truck, effectively allowing Sytsevich to potentially injure or kill numerous people in the process. He even allows Sytsevich to fire a gun out of his window and into the open crowd instead of trying to disarm him as soon as he sees the gun.
Phaneron