One of the Evil Overlord Tips is “My secret lair will have ventilation shafts too small to crawl through.”
Do the people who write these lists realize that henchmen* have to breathe?
Poor ventilation kills a lot of people in poorer countries today. Not only do poisonous gases get trapped, but diseases spread quickly. The army of henchmen will all have pneumonia and influenza within a few weeks if they’re working in a poorly ventilated stuffy lair. Now this may explain the general incompetence of persons of hench, but I can’t imagine any evil overlord intentionally deciding to give everyone the flu. So the lair needs big aircon systems. Which need large vent shafts. Plus, if the evil overlord is manufacturing explosive doom chemicals in-lair, those doom chemicals are going to need ventilation. Does the overlord want to compress his doom-chemicals in high-flow, low cross-section ventilation shafts?
What’s going on here is the notion that I can attack you with common sense, but you can’t attack me. If I point out the security failings of large vent shafts, you’re not allowed to point out that otherwise all of my henchmen will have pneumonia. Teddy Roosevelt had a message about this.
*I say henchmen, because it’s almost always men. If an evil overlord has an army, the movie is going to be directed at men. Therefore the main character will almost always be a man so the primary audience can identify with him. If the hero breaks into a lair and beats up a bunch of male henchmen it’s a good action sequence, but if he beats up a bunch of recognizable human women, it’s problematic. So the minions have to be insects, aliens, other creatures, or men. Male actors in uniforms are a lot cheaper than good CGI.
At least for action movies, but I haven’t seen any evil overlords with lairs full of henchmen in not-action movies. I’m very curious if there are any exceptions.