Stupidity: When formulating his plan to kill the CEO, the Virtuoso posted "lost dog" signs on poles within the area he was going to shoot. When finished, he looked up and across the street to the window from which he was going to shoot. Instead of being "a shadow", the Virtuoso put himself at the crime scene the day before, looking quite suspicious. If/when police looked for surveillance camera footage, the Virtuoso's behavior would be quite obvious. (00:10:23)
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: Paul Manfield (Arthur Pope) and his family have been hiding from and eluding the FBI for fifteen years, but Paul gets so intoxicated one night that he loudly sings "Pretty Woman" walking toward his house - where neighbors could hear - and yells that he is not Paul, he is Arthur Pope. (00:52:18)
Suggested correction: People do seriously stupid things when they are drunk, and Manfield/Pope is very, very drunk.
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: Angela ran over to her neighbor Mr. Charlie when she heard him come home. Angela was complaining that his son and friends make too much noise, do whatever the want, are bringing property values down, act wild/crazy, draw attention to everybody, and she doesn't want the police coming. These may be legitimate complaints, but the way Angela expressed them would bring down property values! Not only was she yelling in the street, she used "m-f-ing" several times, as well as other select words. (00:02:35 - 00:03:07)
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: When Joaquin was running from Cornell, he turned into an alley between buildings. He was to the left (of the screen), which was unobstructed, but ran to the right, so he could jump over boxes. Cornell could have also stayed to the left, but ran far enough to the right where he could kick the boxes out of his way. Easily avoiding the boxes would have been faster. (00:11:37)
Stupidity: It was very idiotic of Turner, who is an experienced serial killer, to not only knock out and take Julie prisoner, but to attack Kale as well, considering the recent circumstances. The police and Julie didn't believe Kale, and Turner suddenly goes on a rampage? He took a huge risk when he attacked Kale and could have very easily blown his cover.
Stupidity: Dirk squeezed a long stream of lighter fluid onto the pile of Mario's clothes, then saw a necklace, which he removed (and potentially got lighter fluid on his hand while doing so). Instead of tossing a match from a safe (r) distance, Dirk crouched next to the saturated clothes and held a match near the bottom of the pile, risking burning himself. (00:06:40 - 00:07:21)
Stupidity: Andy meets Tommy Williams who names another convict who described the scene of the murder of Andy's wife and her lover in sufficient detail to convince anyone that something was wrong with Andy's conviction. Andy then goes to the Warden, a man he knows to be utterly corrupt, a man who will suffer a huge loss if he is acquitted. Andy is an intelligent man - why would he do something as stupid as that? Why doesn't he write to his lawyer? This is a matter for an appeal court, not the Warden.
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: There is a scene about a null hypothesis proving Cassius is the killer. Nearly everything is wrong in this scene. Statistically, you never prove a null hypothesis true. (01:23:11 - 01:24:22)
Stupidity: Instead of breaking into Gordo's house, covering all the furniture in one room with sheets/thin blankets, and waiting for Gordo to return home in order to kill him via a "dramatic re-enactment" (in an adjacent room which was not shown to the audience), Bill could have taken Gordo anywhere to avoid getting caught or calling the police on himself. Had Bill taken Gordo to his already-"wrapped" motel room, he had enough injuries after the fight to claim self-defense against an intruder. (01:43:20)
Stupidity: At the start, when the bank robbers pile into the car, Frank flips a switch and the licence plate changes...out in full view of the public. Given how well-prepared Frank is demonstrated to be, that's absolutely something he would have done in private, before arriving at the bank.
Suggested correction: The plate is changed after the robbery for a reason. By allowing plate A to be seen during the robbery the information will be relayed to the police that a car with registration plate A is involved. Swapping to plate B after the robbery ensures that police will see plate B and know that the car is not involved.
But the point is he drives up to the bank with plate A on display. The robbers pile in and he switches to plate B. So any witnesses have seen both plates (plus the fact that the car switched plates, doubly suspicious). Whereas if he'd switched to plate B while out of view in the car park, he'd still have a "clean" plate to use.
Stupidity: Rick tries to kill Frank at his boathouse by dumping gasoline all over the place and using Ray Coleman's lighter that Frank had. At this point, Rick has gasoline over his arm, but instead of properly cleaning it, he opens the lighter immediately and has his arm burned. Surely a criminal genius like Rick wouldn't have risked this as this is a loose end. Further mention goes to when he has the bathroom door open for no reason while medicating the burn mark, which enables his wife to see him and discover who he really is.
Stupidity: When he's using carbon monoxide to poison the corrupt detective Frank Masters, the windows in the car were operated by the key fob. Unusual, but OK. Maybe. But the detective could've simply opened the doors after McCaul left him in there. The door worked when he was forced into the car. (01:24:30)
Stupidity: When the duke approaches the wall at the end, Snake dives on him and briefly knocks him out. Snake could have easily grabbed his gun back and left the duke unarmed (or even just killed the duke there and then), but just gets up and runs, leaving it with him.