Stupidity: After hearing the question on the radio station to win the Turbo Man doll and a failed attempt at the pay phone to answer it, Howard and Myron end up running two blocks to the station to answer the question. This is really stupid because the prize was going to the first caller with the answer and in the few min it would take to run to the station two blocks away and finally reach the DJ, many calls would have come in and most likely someone would have won already, way before the men arrived there.
Suggested correction: This isn't a stupidity or a mistake. What else did you expect them to do? Plus, the DJ even later asks if they expected him to actually have a Turbo Doll in the studio, and they both said "yes."
Not only that but, Myron had ripped the phone receiver out so Howard couldn't give the answer to the DJ. Howard and Myron running to the radio station was the only other option they had. At that point, it would only be a matter of if they got to the station in time before somebody could call in with the right answer.
It was a very easy question naming santa's reindeer. Although some people may not quite know them all... most people do. Now if it was a relatively hard question, our two guys probably had a better chance. But all good points made here in all these comments.
Stupidity: Jimmy and his friends aren't allowed by their parents to go to the opening of Retroland because it is a school night. What kind of amusement has its grand opening on a school night? It would make more sense commercially to open on a Friday or Saturday night.
Stupidity: Leonardo could use his swords to cut the net when Leonardo, Donatello, and Michelangelo are trapped in a net.
Suggested correction: While trapped in the net, it would have been quite difficult for him to draw his swords from the sheath on his back.
While that is true, him not attempting to reach his swords makes him look like a fool that forgot he has swords.
Stupidity: Captain Hook has a ship full of cannons and other weapons, but he never tries to kill the crocodile trying to eat him. Why doesn't he just kill the crocodile?
Suggested correction: Setting aside the fairytale nature of the story, in which logical holes like this should be overlooked, the crocodile is not available at Hook's convenience, and Hook is too terrified of the croc to seek it out.
Stupidity: If the fairies knew that Maleficent was going to try and kill Rose on her 16th birthday, why, oh why, do they take her back to the castle on that day? Why take her back to where Maleficent was expecting her? Why not wait until after her birthday?
Stupidity: The Foot Clan found the Turtles' hideout in the sewers thanks to one of their members who followed Raphael when he was carrying an unconscious April O'Neil after he saved her from the evil ninjas. When Shredder later is trying to find the Turtles, it takes Danny's betrayal to point him towards April. How stupid does he have to be? It's a connection anyone would have made, it was the second time she was saved, even.
Stupidity: Why would Stanley say the shoes fell out of the sky? It happened under a bridge. Any normal person would instantly realise someone threw them off the bridge.
Suggested correction: It's an idiom/expression. When something turns up out of nowhere, we say "it came/fell from the sky." In fact, Mr. Sir says this to Stanley when he finds Stanley with his empty bag of sunflower seeds, "Where did this come from? Did it fall from the sky?" Obviously a sarcastic way of saying, "it didn't get there by itself, someone put it there." So the shoes obviously fell from the bridge and Stanley knows this because Zero refers to the bridge later in the movie.
Stupidity: Even though Hermione reminds them that they must not be seen after freeing Buckbeak, they fly toward the castle, whooping and cheering because they're flying. Then, they land in the courtyard of the castle, have a conversation, and then Sirius flies off with Buckbeak. Not the behavior of trying to remain unseen and unheard.
Stupidity: The whole movie necessarily has to be filled with stupidity (we're talking about a 9 months kid besting 3 adults), but there's one part perhaps not so obvious and that may be related to a mistake about the ransom note. When the bad guys watch the news, it's obvious that their original plan failed, since they cannot retrieve the money at the designed drop zone, the police have been called and they'd need to rethink the whole operation. Yet they make no comment about it and don't seem bothered by that at all.
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: While being pursued by the Headless Horseman, when Ichabod first approaches the bridge, he could have gotten off his horse and fled on foot.
Suggested correction: Considering that the Horseman's horse is supernaturally fast, if Ichabod had gotten off his horse and ran for the bridge, the Horseman definitely would have caught up to him.
Stupidity: Billy and Allie saw there were several men in the area also searching for the medallion and the kids even hid from the men minutes before finding the medallion. Instead of quickly sneaking away after they found the medallion, Billy and Allie stayed in the same spot and Billy shouted, "We found it! We found it!" Seconds later, two men came from behind the tree. (00:24:00 - 00:24:21)
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.
Stupidity: When Gail shoos Luke off the first day, in fact nobody accompanies him to the door and they discuss the evil plans when he's not even gone nor they even check he is, they just go ahead with the script. It's a rather odd dynamic, very rushed and movie logic-like. Or theater logic, since it's a typical 'exit stage left' moment.
Stupidity: There is no way Mr. Mertyle did not hear the fence in his backyard crash to the ground; there's also a likely chance he could hear his dog crying and Smalls saying the dog is hurt. Even if he could ignore the sounds of other attempts to try to get the ball back; with the fence coming down where his dog lives and the chances of an injured pet it seems far too unlikely he wouldn't have rushed straight to the backyard hearing this.