Stupidity: After Ethan "lands in the future", his spacesuit catches fire. He removes his glass head cover (so he can enjoy the smoke in his face?). Instead of following the well-known "drop and roll" technique for smothering/ putting out the flames, Ethan stood there and patted the flames on his wrists and legs with his gloved hands, but the flames were spreading. His next idea was to remove the spacesuit. After a short struggle getting it off, Ethan was no longer "on fire" - so now he dropped and rolled. (00:29:39)
Stupidity: Wouldn't it be common sense to have more than one remote to control Robo-Cain? That way, if he destroyed one (and he did), they could still use one to shut him down from a distance (as long as they can dodge the gunfire).
Stupidity: All of Robbie's circuits have been burned out as a result of Morbius ordering him to kill the Id monster. The crew only has 24 hours to get the ship loaded and a safe distance away from Altair IV before it explodes. But one or more of the crew spends the little time they have fixing Robbie, a very sophisticated piece of technology, who is working the controls at the end of the movie.
Stupidity: This highly trained squad of soldiers is sent into a known contaminated zone with all manner of chaos going on within in...and the second one of them sees a woman outside his APC he ignores a direct order and pops outside to see how she's doing.
Stupidity: It's mostly a fun absurdity, but it is somewhat contradictory to showcase the Ghostbusters being featured as the cover story of every major publication and news outlet, and yet to get help not only they put an ad on the newspaper, but a single person applies for the job (which is all it took for them to accept).
Stupidity: When Michael is heading to the hospital and he just learns that the Cloverfield Station is gone, the whole scene of him driving is super unreal. It looks like he's not even driving, like it's a self-driving car or something because the steering wheel doesn't move at all while he's driving, and he isn't looking at the road (staring into space). The whole scene just doesn't feel realistic. (00:43:48 - 00:44:30)
Stupidity: After Noah shoots the Humanity Bureau vehicle following them, they continue down the road and stop at an old abandoned building that still has some sort of running water in it. Lucas has to go to the bathroom so his mother just lets him wander off by himself to find a restroom. She doesn't go with him or make sure he's fine. And this is in an area where they know that most of the residents are hostile, and they are being chased by the Humanity Bureau. Noah even calls her out on the stupidity of her letting Lucas go by himself and she claims it's because he needed to do number 2 and that Lucas insisted and he's not a little kid any more... Which doesn't excuse the stupidity of the action of letting an 11 year old go by himself to find a bathroom in such a situation. And ultimately it does lead to him getting found by Agent Westinghouse. (01:08:30)
Stupidity: The Analyst wishes to hide the true identity of Neo from anyone inside the Matrix, so his appearance is altered. But in this new Matrix Neo is also named Thomas Anderson, his name from before he was pulled from the Matrix originally, and he is a famous game developer that created a video game series called "The Matrix." It is frankly astounding that anyone actively looking for Thomas Anderson would not immediately see through this ruse and instead would be fooled by balding hair.
Stupidity: Very soon after Damon is stranded, one of the many satellites around Mars inevitably picks up the fact that he has moved various objects around his site, indicating that he's still alive. Yet it never occurs to him that this would obviously, eventually happen. In which case, his best option would be to simply spell out a message with debris and stay put instead of planning some 50-day journey.
Stupidity: Since we get frequent POV shots from their eyes, we see exactly what the creatures hunting Venom see. Even when the Codex disappears from their view, they can see distinctly Venom's shape, and they have no problem using their appendages and brute force against any and every creature. There are moments in the movie (such as the scene in Vegas) when the Xenophage just stops for no reason; even if the big blinking thing is gone, you can still see the shape it was attached to.
Stupidity: Central to the plot is the layout of the Mars lander. There are no seats or any restraints of any kind in the lander, which is ridiculous. Spacecraft require safety belts in order to prevent astronauts from being injured during rapid course corrections. Additionally, ordinary rolling desk chairs would not be sent into space, and would certainly not be placed on a landing vehicle.
Stupidity: Whilst the chaplain and one of the marines are talking in the kitchen, a demon sneaks up behind the marine, stabs him through the back and kills him. The demon then walks up to the chaplain and strikes him across the face and leaves the room to search for the rest of the crew. Despite the intent being to kill the crew, the demon does not make sure that the chaplain is dead before leaving. It just assumes the strike across the face will be enough to kill him.
Stupidity: Stitch wakes up in a kennel with dogs at the animal shelter. When Lilo picks him out and they walk out of the kennel, the lady freaks out and tells Nani, "We thought it was dead, it was hit by a truck!" So, what was thought to be a dead dog was put into a kennel with other living dogs. Think about that for a second. (00:24:54)
Stupidity: I won't begrudge Father Lamont for instinctively grabbing for the first thing in reach to try to smother the box on fire (even if it is a pair of wooden crutches), but you'd think at some point he'd notice that he's just spreading the fire and making it much, much worse, but he keeps at it until the doctor finally returns with the extinguisher.
Stupidity: Project Pegasus is a billion dollar structure with no security guards besides the couple dudes Fury shows the badge to at the entrance, no video surveillance, and once SHIELD arrives nobody has to even open a locked door anymore.
Suggested correction: First of all, Fury was allowed in as it's a government facility and he works for the government and as a SHIELD agent is allowed access. It's inside a mountain and they passed multiple security guards as they drove in, armed guards. Everything is thumb prints and cameras which was quite elaborate for that time. To say they lack in security is quite an understatement. SHIELD has quite some authority and can easily take control in the Pegasus project facility.
You are right about the main entrance being truly secure both for guards and strategic position. The problem is that they are free to just roam the facility for an hour, blast through doors, not a soul in sight, no evidence of camera monitoring the inside of the structure, and once the gag of the pad is finished, no door requires it. Actually, funnily enough you can see a guard of the place opening the elevator for Fury and the supervisor, as if the thumprint scan was needed to even get into the elevator itself, but Keller then just walks into the archive just fine (from a different door than the one Vers blasted). There are keypads to exit places (for instance the hangar, when the agents in pursuit break through the door you can see a keypad on the wall) but only when it's convenient (Vers and Fury walked through that same door with no problem, not to mention the fact that the whole stairs seem to have none, which is funny for a place that has keypads both sides of doors).
Stupidity: Harrigan leaves his partner's badge on his grave where anyone could take it and use it to impersonate a cop or abuse it in other ways. (00:50:15)