Stupidity: At the end Vince fires a grappling hook at the passenger seat of the truck then attaches the other end to himself, all the truck driver has to do now is hit the brakes and Vince would be dead under the truck or dragged along the road.
Suggested correction: In point of fact, the truck driver does slam on his brakes; but, defying physics, Vince is catapulted around the right side of the truck to the passenger door.
Stupidity: After Jack is found not guilty, you would think the first thing he would do is to get rid of the typewriter he used to send the notes to Teddy to manipulate her into winning the case for him, especially when she is sleeping with him at his home. Not to even mention the fact he hid the typewriter in an unsecure manner in a closet behind a stack of towels, a place where it would very easily be found. This foolish mistake exposed the truth to Teddy and cost him his "freedom."
Stupidity: After Roy escaped from the factory, he encountered a metal garage-door-type gate that was open at the bottom to the height of his knees. Trying to sneak away and in obvious pain from his injuries, it would have been quicker, quieter, and probably less painful if he crawled through the opening. Instead, Roy pulled downward on the chains, making a lot of noise, and it didn't even get the gate halfway up before he bent over to get out. The gate went up more after he stopped pulling on the chain. (01:15:29)
Stupidity: When Drake cuts off power to Hayes' apartment, the cops can't physically make a landlord abide by the laws, and seeing a judge would take months. In the meantime, by keeping the power off in the apartment, Hayes would have had no choice but to abandon his scheme and move on to another victim. With no power in the apartment, it's unusable and unlivable.
Stupidity: I seriously doubt that any Mexican Mafia cartel operating here in the U.S. would waste their time eliminating two simple patrol officers. There's nothing to gain by doing so, and it would bring a war between themselves and the police, which in return would bring hundreds of arrests of key members, drug busts, raids of their operations within Southern Cali, etc. They wouldn't risk their business taking millions of loss of revenue all to kill two patrol beat cops.
Stupidity: When Steve Martin reaches the beach with the wheelchair, he tips it over, giving the illusion that he fell out of it. However, with where he starts crawling on the beach, it's tipped the wrong way. If it was that way, he would've been on the other side of it. A clever con-artist should know better.
Stupidity: The protagonist has a sophisticated alarm system with cameras...that do not properly show who is at the gates (the cameras are positioned in a way that does not show the face of the person ringing). The bad guys are disguised as police officers...and wear ski masks, which would have made the disguise entirely pointless - but luckily for them, Nicholas Cage can't operate cameras nor looked at the ones on the entryway or the front of the house, didn't open the door sooner nor peeps before opening. They could not know any of that, though, just that the camera at the entrance has a terrible angle.
Stupidity: Joe's second homicide aims to be ruled as accidental death, but Joe's plan involves a furious struggle with the guy underwater, who claws and bites at his arm, as he applies pressure to his shoulder and neck. Moreover, their struggle happens close to the water surface but the bodyguard who is there does not hear or see anything. (00:35:00)
Stupidity: Jimmy parked his truck on the side of the road with woods running parallel and starting about 10' away. Jimmy moved to the passenger side so the Sheriff could sit in the driver's seat (for no apparent reason). After Jimmy threw the "white powder" into the Sheriff's face, he quickly got out of the truck and ran straight ahead on the road instead of ducking into the nearby woods. The Sheriff had a clear and easy shot to hit and kill Jimmy. Also, Jimmy should have been much further away. (00:11:51 - 00:12:21)
Stupidity: Sherlock Holmes, a "simple" detective, knows the whole story of an English officer and that of a Nazi secret agent and their great physical resemblance, but Barham's colleagues in British Intelligence do not know any of these facts and are surprised when Holmes tells them all the details.
Stupidity: Early in the movie, AMMO and its crew show remarkable prudence in their approach to the drug deal, and a point is made about them following procedure, planning accurately using technology and trying to minimize collateral damage. The sting at the club goes against all of that. At the end of the day, it just consisted of getting close to the target and pulling guns on him in the middle of a crowd of civilians, the exits of the place (the front door even) completely unguarded.
Stupidity: Felix and the DEA capture Sanchez, a very powerful drug lord, in a very public way, have the wedding...then everyone just goes home. No concept of extra security or concern about his minions getting revenge. So of course they can then just wander into his house with no problems whatsoever to capture him and murder his wife. Bond's clearly concerned when he learns Sanchez has escaped, but he must have realised there'd be plenty of goons still around before that point.
Stupidity: After the Defranco "assassination" Rollie learns he is a target and survives two attempts on his life. But instead of leaving town or finding somewhere else to hide for the night, he spends the night in his own apartment (even though he was well aware the killers knew where he lived). As a result, his girlfriend is killed and he barely escapes alive.
Stupidity: Noah chases one suspect while Leslie chases the other two. Noah eventually pulls out his gun and says, "Stop, police!" Leslie doesn't even try to draw her weapon until she hears sounds from the nearby brushes - but she barely has her hand on the holster when she turns around and gets punched in the face. Leslie is knocked over and the other man she was chasing repeatedly hits her in the face, quite hard. Her injuries could have been avoided simply by having her gun ready to aim and use. (01:04:48)
Stupidity: The protagonist knocks at every door, humiliates himself, losing any hope of getting his dream job, jumps through all sorts of hoops to get a court order to save Crawford's wife, but somehow, once he gets it, he has to drive through LA and physically get to the hospital room where euthanasia will be performed, because he couldn't be bothered to phone the hospital to tell them about the court order or talk to someone in the lobby.
Stupidity: When Poirot's team attacks the Germans, they do it through the cover of gas they release. The Germans are having a good time chatting and not taking the situation seriously when there's a big cloud of noxious gas advancing towards them. Despite Poirot's oh-so-clever plan, they should by all means know that something is coming their way, but they get caught entirely with their pants down.
Stupidity: The first time they see the bad guy in the Land Rover, Morgan has him in his sights but can't shoot, as he doesn't want to kill him. Clearly, the obvious thing to do is to shoot the car tires, but he doesn't and lets him drive off.
Suggested correction: Shooting out car tires is not an actual effective strategy to get a vehicle to stop. A 9mm bullet simply doesn't cause enough damage to a tire to get it to go flat immediately. It causes similar damage as running over a nail. It is a movie cliche, similar to using a gun to shoot out a lock or a rope, it just doesn't happen in real life.
Stupidity: When Alice opens the door for the dumbwaiter, how did she not see the bottom of the elevator was removed when she was looking right at it? She even realised it was missing as she was getting in, but she still let go and fell to the basement.