Stupidity: After Julie tells Louis that Peyton is still alive, she notices the Bellisarius memorandum on his desk and realises he was involved with the destruction of the lab. If Louis had kept the memorandum in his desk instead of in plain sight, he would never have been found out.
Stupidity: When a cop goes to Kevin's house after being requested by police, he simply knocks on the door and after a few seconds walks away assuming no ones home. Had he actually bothered to announce himself as a cop, Kevin would have opened the door and he would have been found safe.
Stupidity: During the final battle, Gomm kills one of the rednecks by sticking his tentacles into the man's eyes. However, the entire scene is shot very sloppily. The man has his gun trained on Gomm for almost 10 full seconds, and just stands there while the tentacles come out slowly, Gomm laughs, and then the tentacles shoot forward. Given the amount of mayhem and creatures, there's no reason for the redneck to have not just shot Gomm during that period of time.
Stupidity: The system prompts a message for the bank clerk saying that the subject trying to withdraw cash is armed and dangerous and to alert the local authorities. It also alerts the 'subjects' themselves though, since it beeps a persistent alarm tone! Seems a rather poorly designed system that would endanger the staff. (00:50:10)