3. Why Didn't The Microwave Emitter Kill Everyone? (Batman Begins)
This is one of those plot holes that people picked up on instantly; I recall leaving the cinema back in 2005 and one of my brainier friends instantly started harping on about it. The villainous scheme at the film's climax sees Scarecrow (Cillian Murphy) and Ducard (Liam Neeson) attempting to spread a nerve toxin through Gotham City by dumping it in the water supply and then using one of Wayne Industries' microwave emitters to vaporise the water, allowing the toxin to disperse. But wait, we're forgetting one very important, commonly known fact; depending on age and size, the human body is composed of roughly 65-75% water, so surely, when the emitter was switched on, it would have killed every single person living in Gotham? There's not really any way to get around this one; given the intelligence of Nolan's films on the whole, you think he would have come up with a more plausible way to transmit the toxin even if it wasn't as snazzy and theatrical.