Stupidity: At the end, the police inspector talks Bruce Lee into surrendering, and about 8 people (including the inspector) escort him out of the school. As soon as they're outside, Bruce sees a formation of heavily-armed police preparing to fire. Realizing he was betrayed, Bruce Lee charges, screaming, straight into a barrage of gunfire as the action freezes for credits. However, before the action freezes, there's NO reaction from anyone standing behind Bruce Lee, even though they are directly in the line of fire. Even the police inspector (who knew the police gunmen were waiting outside) just stands there instead of immediately diving for cover.
Stupidity: Crystal knows she is being hunted and in a very dangerous life-threatening situation yet, after she kills "Ma and Pops" in their Main Street Market, she grabs only a few shotgun shells out of the open box instead of taking all of them or as many as she could find. Also, she walks some distance to the store but did not take anything to drink or eat. (00:27:00 - 00:27:55)
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: A load of cars is in the tunnel with the overhead lights off, and none of them has thought to put their own lights on (as covered already). Then John gets out of the car, only for one car to suddenly flick its lights on and nearly run him over, having been driving at full speed in the total darkness, apparently.
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: Molly was being hunted and didn't know if she could trust Rayburn when he encountered her. Rayburn told Molly that he wanted to help, wouldn't hurt her, put a blanket around her, and even carried her in the woods for some distance. When he put her on the ground (along with his backpack and rifle) to go find the rope to open the pitfall doors and had his back turned, Molly got out from under the blanket and hid nearby. Rayburn quickly found Molly, and Molly made a lame attempt at attacking him with some kind of club. The next day when Rayburn and Molly were in Rayburn's house and her hunter showed up and attacked Rayburn, Molly grabbed Rayburn's rifle and fired several shots at the hunter. Molly obviously knew how to use a rifle, so it was asinine for her to have hidden from Rayburn the previously night without taking his rifle (or the blanket). (00:36:22)
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: 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: Agent Toby Lee Shavers guides XXX through the wrecked military complex constantly telling information that Ice Cube should already know perfectly as essential basic mission objective data, such as the location of Gibbons' office and which hard drive to grab out of 3. Would be fine if Darius told him to shut up, but he does not, apparently he needs the infodump. (00:21:20)
Stupidity: The security system is able to automatically ascertain the malfunction to the exact valve, and the electrical problem, but the alarm is not triggered at that point, but only when the holding cells are already filled with water and Breslin is making his return. They are on a ship, the fact that it's taking on water feels like a pretty important issue to monitor.
Stupidity: The patient was wearing a white and gray striped tie when he was walked into the ambulance. The EMT did not remove or even loosen the patient's tie (to facilitate breathing). Instead, the tie was moved from the front to along his shoulder/neck, apparently to get it out of the way while she was cutting off the patient's shirt. (00:07:50 - 00:08:20)
Stupidity: Milton, straddling Edie's body on the floor, is about to pull the plastic sheeting over her head. Edie's eyes suddenly open, and she starts screaming. Instead of quickly pulling the plastic sheeting over her head and suffocating her, Milton half-heartedly struggles to control Edie's hands, which she somehow manages to raise from alongside her body and around his to be in front of her neck. (00:38:50)
Stupidity: When Liz sees the dead deer blocking her lane, instead of merely going around it (using the opposing lane on a rural road without jeopardizing her safety), she exits her vehicle - leaving her three-year-old daughter unattended in the back seat - to "look" at the deer. This furthers the plot by giving the "werewolf" opportunity to attack and kill her... as well as her daughter Miley. (00:42:35)
Stupidity: If Leo wants to kill his son's killer at any cost and no matter what happens, he should've gone directly to his House when the purge starts.
Suggested correction: He absolutely is headed there, but we see at least one incident where his path is blocked due to people out purging, and he needs to turn around. That detour caused him to go a different route, which led him to the mother and daughter. We even see him struggling with the decision on whether or not to help them. He decides to do so, and the rest of the movie unfolds as we see, but there is no mistake.