The System - S1-E2
Stupidity: The plot hinges on the fact that even Frank Marley's most trusted man would doubt him because of his actions, but he and Marley counted the money together; he should know that Marley was right and the amount declared was not lower than the actual money deposited. Instead, he is fooled like everyone else by the extra 25K$ planted by the IMF team. Their plan can't work unless he is oblivious and/or forgetful.
The Killer - S1-E1
Stupidity: To make the hit, The Killer places a bomb on the ceiling of his room - which is the floor of the victim's. He has absolutely no way to know where in the room the man will stand and when we see the explosion, it does not even touch the couch. The brilliant plan of the flawless killer is anything but brilliant or flawless.
