15 Infamous Movie Plot Holes (That Actually Aren't)

11. Why Doesn't The Microwave Emitter Kill People? - Batman Begins

The "Plot Hole": Ra's al Ghul's plan involves stealing a microwave emitter which he will use to vaporise Gotham's water supply, turning the toxin-laced water into vapour which will disperse throughout the city and turn its citizens crazy.

But given that humans are roughly 65% water, wouldn't the emitter also kill just about everyone in the vicinity?

Why It Actually Isn't: It's mentioned that the emitter was originally designed to evaporate an enemy's water supply, essentially suggesting that the microwaves can targeted in a very specific fashion.

And on top of that, humans aren't literally full of water in the typical sense: it's present in various forms within the body, and so may not be susceptible to being vaporised as a result.