Stupidity: Granted, Coffee is suffering from "high-pressure nervous syndrome," but if you're a Navy SEAL, wouldn't you notice whether or not your pistol has a magazine in it? Monk pulls the clip out of his jacket and starts knocking rounds out of it for the rig crew's benefit; the same dramatic effect could have been achieved with a handful of cartridges he could let slip through his fingers. You could argue that Monk didn't have enough time to unload the gun and replace the magazine, but in that case, I think the scene where Monk briefly had the gun should have been a bit longer. (Even had the empty magazine been IN the gun, Coffee still might notice the difference in weight, but that would be easier to suspend your disbelief for.) (01:43:53)
Stupidity: It was pure stupidity for Riggs to bring Rika back at her residence after escaping the hit on Riggs. The villains know where Riggs' love interest lives and this nor the option to hide somewhere else or safer never occurs to him?
Stupidity: At the start of the tanker chase Sanchez shoots at Bond. He manages to get in the cab and throw the driver out, who lands on Sanchez's car. Sanchez then gets in front of Bond and has the ideal opportunity to just shoot the cab up with his machine gun knowing Bond is driving, but he doesn't.