I mentioned this in another thread of mine, but there's a fun episode of Doctor Who I just can't enjoy with all my heart because there's a huge, glaring plothole at the end. Long story short, nearly every human on earth has been given a heart attack by electromagnetic pulses given off by little cube-shaped machines. The Doctor manages to send out another pulse which restarts people's hearts and saves the world. HOWEVER, never at one point does the Doctor or anyone else address the fact that people's hearts were stopped for several minutes before the Doctor managed to start them again.
Never once do they mention how after 3-4 minutes without a pulse a person becomes brain dead, never once do they mention any amount of time that can't pass before they're too late. No, they have a good long monologue between two characters before people are brought back to life, with no mention of brain damage in sight.
This could have easily been fixed with a quick mention about brain damage while the Doctor is explaining his plan to send out another pulse, and he could have spouted some technobabble to explain how the pulses also saved people's brains. But nooooo, they just ignore it, and I'm feeling really insulted as a viewer. Like SERIOUSLY Doctor Who writers? Do NONE of you really know anything about what happens when the heart stops beating? NOBODY caught that one before the script was approved, or when the actors did their first readthroughs?