Stupidity: When White and Exley meet outside the motel and realise they've been set up, White suggests they leave, but Exley says it's too late. It wasn't even close to too late. There were no other people around, they had cars and there was a road right in front of them. Then they decide to go trap themselves inside the motel. It seems like they wanted to be shot.
Stupidity: The bad guy's henchman has a plan to stop XXX from reaching the wagon with the President. He hides in the kitchen compartment, which is in a separate area that XXX has to decide to look up and get inside of for no reason (guess that looking at Ice Cube he guessed he'd be going for a snack at some point), leaves his automatic weapon on the floor and just waits there in a ceiling compartment with a knife. If he just shot him through the wall or the door, I guess it would have been too easy. (01:26:20)
Stupidity: The kidnappers steal a silver Citroen van and take it to a junkyard to switch the plates. They steal plates off an older green color Asian type sedan and place them on the van. If the cops run the plates as they normally do random checks as they drive, those plates will not match that vehicle. They should have found the same make and color of Citroen van they stole and swapped plates for plates, the chances of the owner noticing are small. Now if the plates get run they match that vehicle. (00:00:38 - 00:01:18)
Stupidity: Soon after the new art therapy instructor Anna arrived for her first day at the mental hospital, Leena - the most dangerous patient - was not in her room and nobody could find her. The hospital went into lock down and the doctor took Anna to a room. Without first looking in the room, the doctor said, "Do not leave this room. Don't worry, you will be safe here and we'll come back after we found her" and then locked Anna inside the room - with Leena. (00:03:36 - 00:04:41)
Stupidity: When she leaves him at home with a sandwich she says people will come check on him. When she gets home and he's not there, she doesn't go and ask those people where he is.
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: When Jonathan is chasing the truck to try and save Sarah, he could have removed his heavy backpack and run faster...but instead just leaves it on. No wonder he wasn't fast enough.
Stupidity: Anyone with a job in the White House would have to be known to the Secret Service on a daily basis, so the two Secret Service agents that find Cory the janitor should have been aware of his identity without him having to state who he was and that he worked there.
Stupidity: After Casi changed the tracker on the Navigator, he was sneaking between vehicles to get out of the tow pound. The Whale came and stood in front of the two vehicles Casi was between. Casi stood up and, instead of turning around and running away, rushed TOWARD The Whale in an attempt to get past him. The Whale, much bigger, threw Casi against a vehicle and then onto the garage floor. (01:03:34).
Stupidity: One of the major reveals and plot twists of the movie lies in the fact that a certain character is an accomplice of the medium. The reveal, though, does not explain at all how said individual managed to fool Poirot; the trick briefly shown involves a simple rope pull to open a door. Poirot was looking exactly for that kind of trick, paces around the room constantly on maximum alert, and examines the door itself later. Likewise, it does not explain where and how they could hide the stuffed animal.
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: Dr Faxx knew full well that Nuke was Cain's greatest weakness, but it never occurred to her to mention to the old man that holding a canister of it in front of him during the exhibition could have serious consequences. Not very bright.
Stupidity: Why does a safe house have a skylight? It is a secure building with hardened doors but a window in the roof?
Stupidity: The crack house workers are all topless to prevent 'hiding' any product for personal use. Yet are also wearing parachute type pants that they could easily hide things in.
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: When Drake cuts off power to Hayes' apartment, the cops can't physically make a landlord abide by the laws, and seeing a judge would take months. In the meantime, by keeping the power off in the apartment, Hayes would have had no choice but to abandon his scheme and move on to another victim. With no power in the apartment, it's unusable and unlivable.
Stupidity: Given Enchantress' power, why not just try to cure Dr June Moone, so she can't threaten the world? That's what the government should've done.
Suggested correction: We're talking about Amanda Waller who had no issues murdering innocent government employees that were accidentally exposed to her top-secret Suicide Squad program they weren't cleared for (versus making them sign an NDA not to talk about it as in a real-life accidental exposure to uncleared employees). Waller just took the easier option which was to threaten to kill Enchantress if she didn't obey versus spending countless dollars (and exposing more people to Waller's program) trying to cure her.
Stupidity: When they are in Italy on the boat, they find out they need to go to Montecarlo in order to reach Switzerland. They have a chopper. Italy is right next to Switzerland. It makes no sense that they would take a boat to Montecarlo to get to Switzerland, especially given the weather they'd have to sail through.
Suggested correction: We don't know where in Italy they are. If they are all the way in the south, there is no way a helicopter could make it to Switzerland on a single tank. Then he would also have to consider clearance for airspace, where and how to refuel etc. In short, sailing to Monaco and flying to Switzerland from there is much easier.
Clearance to dock in Monaco is needed if you sail with a large ship. Same trouble than air clearance. Using a helicopter is still faster, even with the eventual refuelling. Switzerland via Monaco makes no sense. They would still need to use the helicopter or a car from Monaco on.