Stupidity: When Colonel Hardy is about to crash the ship he's flying into a building, Faora sees it and she has more then enough time to leave the ship and get to safety, but she does nothing and just stands there.
Stupidity: Lily dying at the end seems poetic but it would obviously cause legal trouble for Lucas and Annabel. The court/CPS would still be checking in on the girls, making sure that Lucas and Annabel were responsible guardians. There's no possible way that they could explain the disappearance of Lily. Victoria would certainly be removed from their care and there would be legal action against them, as negligent caregivers. (01:30:00 - 01:40:00)
Suggested correction: Except, of course, if Lily's body is found and her death is determined to be a tragic accident.
Her body can't be found though, because when she died, her body ceased to exist and all that was left was a butterfly.
Stupidity: They go to great pains to lock the nodes behind an explosive lock, then have a debate about whether Riddick's somehow broken in. They eventually unlock them, check they're still in place...then just leave the locker completely unattended and unlocked while they discuss plans, and Riddick of course steals the nodes.
Stupidity: Darren could have easily grabbed Ben out of the locker he climbed into by just pulling. Instead, he pushes it inward, causing it to close and allowing Ben to either hold onto it on the inside or lock the locker itself.
Stupidity: Throughout the movie, and especially up on the top of the apartment building before they get rescued at the beginning of the movie, Gerry counts 12 seconds to check if someone has been infected. Just to mention this apartment example, he gets blood on his face and spends more than 12 seconds getting up and to the edge of the roof, plenty of time to become "Zeke." He then counts 12 seconds, as if they would actually matter to his infection.
Stupidity: A trained CIA hitman wants to kill the owner of a bar. Why would he go into the bar during opening hours, ensuring that there are witnesses to be eliminated, when he could break in after hours, use a few less bullets, and have fewer loose ends to tie up? The break-in would also provide a cover story for the kill. All rather unprofessional.
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: When she is getting the boots out, why is she sleeping outside when there is a fully covered wagon right there? (00:10:00)
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: There are numerous snipers on and around the White House. They should have barraged the lawn and wiped out all the attackers on foot with rifles and machine gun fire.
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.