Stupidity: The "body armor" General Ford and others wear is very bulky and appears to be quite heavy with all the attachments (e.g, flashlights on shoulders). With the protective suit protruding perhaps 8", it would most likely restrict/slow movement, contrary to what soldiers need. Moreover, the body may be protected, but there's no protection for the face/head, leaving them exposed/vulnerable. Today's products tend to be lighter, thinner, and stronger, so would be expected in the future.
Stupidity: In the shuttle, when the fountain pen is floating in zero gravity, the flight attendant grabs the pen and puts it in the pocket of the sleeping passenger. She doesn't put the cap on. She puts it in his pocket nib down. Even though there is no gravity, the capillary action of the nib touching the shirt will pull the ink into his clothing and stain his shirt and jacket. (00:19:40)
Suggested correction: Who said it's a fountain pen? 2001 is set in an imaginary future with imaginary technology, one of which might be leak-proof pens.
Stupidity: Why in the world would Tony of all people leave his old suits in storage WITH the miniature arc reactor still inside the suit? This would have served no purpose to Tony since he already has his own arc reactor in his body.
Suggested correction: This is a question which is easily answered; Tony had the idea of putting someone else in the suit (like Rhodey) himself. Plus, it's logical to think he has built multiple miniature arc reactors, after the events of the previous movie. Plus, he can probably just as easily switch from arc reactor to arc reactor in his chest when changing suits, so he has a fully powered arc reactor ready in each suit.
Stupidity: Jake throws Derek overboard to distract the piranha, then swims under the boat and doesn't get attacked, so why couldn't he just go downstairs the normal way and have Kelly swim over to him? They could have escaped a lot more easily.
Stupidity: Unless Snow has solid proof like pictures or video why should Katniss believe her main enemy's word that it was Alma Coin, not him, who killed those kids?
Suggested correction: This is a question and not a stupidity. Katniss didn't just accept Snow at his word. Earlier Gale had mentioned an attack strategy to inflict maximum casualties on medics that matched the attack on the Capitol. Then Gale could not deny his part in Prim's death. All the evidence pointed to Coin being responsible as Snow suggested.
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Stupidity: Robin uses the high pressure water from the pump to neutralize the bear next to Batman (which is like 10 meters away from him and still the water jet is so strong that it pushes the 1000 pounds bear away and flips it on its back,), but does not use it to push away the other bear that is literally breathing on his face centimeters away from him. He has all the space and time to do that (especially after Batman's intervention). (00:50:30)
Stupidity: Cobb convinces Fischer to enter a dream saying it's Browning's dream. A couple of scenes later he says it's Eames' dream, in front of Fischer, who doesn't know Eames was impersonating Browning. (00:51:35)
Suggested correction: Firstly, the Browning that the team "catches" is not Eames, it is a projection of Fischer's subconscious. Eames was only impersonating Browning in the first level. Secondly, Cobb doesn't say they are going into Browning's dream, he says they should put him under and do to him what the kidnappers were planning to do to Fischer. That is, use Fischer as the subject of the next dream level. Fischer knows that Eames is the dreamer on the third level, he even jokingly asks why Eames couldn't dream of a beach. But he thinks that Eames is part of Mr. Charles' security team. He believes that Browning is to be the subject on the last level when in fact, Fischer is the subject on each level. Because of how effective the Mr. Charles gambit was, Fischer is unaware that the team has been fighting his subconscious all along.
Stupidity: This film portrays Michael Jordan and his family living in a relatively modest house in the suburbs. Jordan was one of the most famous people on the entire planet around the time the film takes place. Living in such an area would lead to a never-ending onslaught of overzealous fans, paparazzi, and even detractors.
Stupidity: After Corinne Dufour realises that Drax intends to have his dogs kill her, she inexplicably attempts to flee on foot, running right past the golf cart she arrived in. The golf cart would have given her more speed, range and protection, and would have been a much better choice for fleeing.
Suggested correction: Golf carts are very slow, and are open on all sides: the dobermans would've easily dragged her off it. The biggest stupidity here is that she should've fled to a crowded area with other people instead of the woods. Then again, she was panicking, and not thinking straight.
Stupidity: When Joan and Winslow are walking through Level 2 after the monsters begin attacking them, at one point Joan turns around and shoots at a monster, but she misses and the monster is able to hide. After this she turns back around and continues to walk down the corridor. The monster she shot at isn't dead, it's just hiding, but instead of going to inspect where it ran off too, she decides to walk in the opposite direction, putting herself at risk of the monster sneaking up behind and attacking her.
Stupidity: Why is it that runners wait until their 30th birthday to run, when they'll most likely get caught? It would make more sense if runners tried to escape to sanctuary weeks or months before their last day. This way, they could meticulously plan their escape without drawing attention to themselves.
Suggested correction: That wouldn't be particularly advantageous for runners. The computer system monitoring the city knows when someone is running regardless of their age and will dispatch the Sandmen to eliminate them. People who choose to run only do it as a last ditch effort, believing they will die on Carousel anyway so running is a risk some are willing to take. In the meantime it would be preferable to live out their guaranteed lifespan and enjoy the pleasures afforded to them by living within the city.
Stupidity: Throughout the movie, and especially up on the top of the apartment building before they get rescued at the beginning of the movie, Gerry counts 12 seconds to check if someone has been infected. Just to mention this apartment example, he gets blood on his face and spends more than 12 seconds getting up and to the edge of the roof, plenty of time to become "Zeke." He then counts 12 seconds, as if they would actually matter to his infection.
Stupidity: When the Woolworth Building collapses and the gang runs into the convenience store to take cover from the dust, Marlena was last seen behind Hud and with Lily, Rob, and Jason. Switch to everyone running from the dust cloud, Marlena didn't make it into the store. Upon exiting the store, the gang finds Marlena stumbling from nearer to the Woolworth Building meaning she would have had to run toward the dust cloud, through the screaming crowd which was running away from the building.