Stupidity: Ashley Judd finally tracks her husband down and what does she do? She doesn't try to capture him to prove her innocence, she doesn't notify the police, she doesn't take his picture and send it to every police dept in the US, she doesn't even follow him to find out where her son is. Instead all she does is ask for her kid back. What was she going to do even if she got him back? She is still on the run from the law, with little money and resources and she doesn't even know if her kid even remembers her.
Stupidity: When Cathy, Chris and Carrie go into their late grandfather's room, they discover a copy of the grandfather's will that states that if it was ever discovered that Corrine had children, she would lose everything. Had they taken the will to their mom's wedding and showed it to her fiance, they would have been able to expose the scam much quicker. Instead, they take the dead mouse Fred with them and show it to everybody. What good would a dead mouse do when a will has more leverage?
Stupidity: In the scene where Billy, Stu and Sidney are in the kitchen (when Sidney finds out they are the real killers), they begin to stab each other as a part of the plan to fool the police into thinking they were almost killed by Sidney's father, whom they were going to frame for the murders. They were planning on killing Sidney and her father, so it makes absolutely no sense that they begin stabbing each other BEFORE killing Sidney and her father, especially since Sidney would be at more of an advantage of outrunning them should she have the opportunity to since they have both been stabbed multiple times.
Stupidity: When Dr Loomis and Sheriff Bracket are chasing who they think to be Michael Myers, you can tell that it isn't him. Michael Myers is supposed to be 6'2 - Ben Tramer is maybe 5'4. If Michael was shot 6 times there would be blood on his overalls. And the mask that the kid is wearing has blonde hair, whereas the mask Michael wears is brown.
Stupidity: When Ruth catches Chuck fishing for turds in their toilet, he yells at her and asks for privacy and then slams the bathroom door shut. He should have closed the bathroom door in the first place if he didn't want anybody to see what he was doing. It's not like anybody would think he was weird for going into the bathroom and immediately closing the door.
Stupidity: Jill wasn't thinking too clearly when she plans her story. She only wiped the fingerprints off the gun but they would be all over the tape on Trevor's body. Then she wipes off the knife yet touches it again to slide it across the floor. She was thinking that Trevor and Charlie were going to be thought of as the killers but their fingerprints weren't on either of the weapons.
Stupidity: When the parents knew Freddy was doing the killing then why didn't they watch him like a neighborhood watch so they could catch him trying it again, and thus avoid the legal technicality which threw out of the first case? It seems idiotic they broke the law to punish this lawbreaker.
Stupidity: Ghostface ambushes Sidney and her friend with the two detectives protecting her while in the car. Ghostface busts out of the driver window, and slashes the throat of the driver detective and then assaults his partner, kicking the crap out of him. Ghostface is obviously going with the intent to kill and has a weapon. He just killed one of the detectives and threw the other in the street in front of the car. When Ghostface jumps in the car to take off, the living detective, beaten, jumps up with his gun trained on Ghostface. But rather than do anything smart, he just yells at the killer, the cop killer, to freeze and get out of the running car that he's standing in front of. He just saw the guy kill his own partner and knows he is intending to kill the girls in the back. His gun is pointed at Ghostface who is about to drive over him, but he just yells at him instead of shooting.
Stupidity: You'd think that Jezzie would have been a little smarter as a secret service agent. You know, like once they acquire Megan, to delete all the incriminating evidence sitting back on an unattended computer. Aside from the fact she also used quite a stupid password, a single password isn't very secure at all. And then the content, displayed instantly when you get in, might as well say things like "hey look, we know what the kidnapper looks like" and "wow, here's the boat he's in too" and "wow, a cabin for sale. Why don't we go hang out there with all the evidence." Come on....they might as well have left a trail of breadcrumbs, because they sure were asking to get caught.
Stupidity: In the opening robbery, killing the third guard made no sense. Even if they didn't kill anyone, they'd still already committed a serious crime, that would result in lengthy prison time if caught. It makes no sense that they have no problem leaving witnesses when they're guilty of armed robbery, but don't want to when they're guilty of murder. If they didn't kill the third guard, their chances of getting caught would've been the same as if they didn't kill anyone.
Stupidity: Dr. Horniker (MD, PhD) advised Mr. And Mrs. Lisbon that Cecilia could use a kind of "outlet outside the codification of school" and should "interact with males her own age." The Lisbons did arrange a party for Cecilia, but the boys who were invited (or came) were somewhat older. Cecilia, at age 13, would be in Jr. High School. Tim and Parkie were 16-17. Chase looked a little younger than the other boys, but none of the boys were really "males her own age." Had the boys been 12-13 or even 14 and Cecilia's older sisters not present, Cecilia may have a better experience - and not jumped to her death during the party. (00:07:35)
Stupidity: During the ghost chase montage, why would Velma look for her glasses with her hand in midair instead than on the ground? No matter how nearsighted you are, the closest wall, or obstacle, is meters away and you'll never find your glasses anywhere but the floor. She does it for a longer time than anyone would. (00:52:40)
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: If the weak spot of the house is the fiery chimney, then why did the kids have to light the dynamite? They put themselves in unnecessary danger for the sake of drama.
Stupidity: Both parents, Dr. Clark and Grace, separately told Lucy that James was a "very sick and dangerous man" and she was to lock all doors and stay inside. When James knocked on the door, Lucy was thrilled to see him and let him come inside the house, totally ignoring her parents' warnings.