Stupidity: When Flint Marko is escaping from the police, he climbs a chain link fence into a test facility. Besides having a chain link fence, there should have also been security cameras around the area as well as guards to prevent anyone from trying to get in. Plus, when the scientist notice on their computers that there's an increase in mass, one of them simply assumes it's a bird and then they continue their experiment. Instead of making assumptions, they should have halted their experiment and have someone take a look to see what caused the increase of mass.
Stupidity: When Stuntman Mike is taking photos of the girls, he is shooting with the lens cap on the camera.
Stupidity: (SPOILERS) Despite knowing that Rowena killed the last person who was blackmailing her, Miles tries to use her secret to blackmail her into sleeping with him. Did he really believe that she wouldn't react with such drastic measures like she did before?
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: The protagonist knocks at every door, humiliates himself, losing any hope of getting his dream job, jumps through all sorts of hoops to get a court order to save Crawford's wife, but somehow, once he gets it, he has to drive through LA and physically get to the hospital room where euthanasia will be performed, because he couldn't be bothered to phone the hospital to tell them about the court order or talk to someone in the lobby.
Stupidity: Mason should have also removed the other gun he had in his office for display, or he could have removed the bullets from the guns. There is no reason he would have to use these guns for his victims, so it makes no sense to leave the other gun in his office or have them loaded with bullets.
Stupidity: If Gabriel and his crew are such incredible hackers, why in the heck would they use a government vehicle that is LoJacked? Even so, wouldn't they be cognizant enough to disable the GPS tracker just in case?