For over a century now, science fiction has been pretty good at predicting future developments -- from rockets that can fly to the moon to little machines we can use to photograph our genitalia, many of the most impressive advances in technology started out in the imagination of some nerd/writer.
However, there are some admittedly cool future advances presented to us by sci-fi movies that we hope never come to pass, because when you stop to think about them, they would cause more trouble than they're worth. For example ...
6The Dark Knight Rises -- Batman's City-Destroying Reactor Has No Safeguards
In the years following The Dark Knight, and faced with a dwindling supply of masked criminals to fight, Batman sets out to punch economic disparity in the face. Under his identity of billionaire/occasional beard-haver Bruce Wayne, he develops a fusion reactor capable of meeting Gotham's energy needs at a fraction of the current cost.
"Half that energy will go toward powering my Batc- uhhh, Jacuzzi."
When a Russian physicist proves that fusion reactors can be easily modified into massively powerful nuclear bombs, Wayne decides to abandon the project and hides the reactor, taking the precaution to add a button that floods the chamber in which it's stored to make sure it isn't used for evil purposes. It's not Batman's fault that someone later figured out how to bypass his security and used the thing to turn Gotham City into an even bigger shithole.
Wait, no, it totally is his fault, because there was no security. Wayne just dumps this incredibly powerful nuclear bomb in an empty basement under a huge city and forgets about it. Yes, it's hidden (accessed by a secret elevator), but that's pretty much it. There are no security guards visible anywhere.
Lucius Fox explains that the chamber "can be flooded in case of a security breach," which sounds great, only that feature stops no one. First Bane steals the reactor, then when the "flooding" mechanism is activated later, it's so slow that even elderly businessman Lucius is able to get away from the room before getting even slightly damp.
"My shoes, your parents ... we've both suffered terrible losses."
Hilariously, when they're showing off the device and the security, Talia says, "Is Bruce Wayne really that paranoid?" That wouldn't have been our reaction. Keep in mind, it took about the same amount of effort to turn this reactor into a nuclear bomb as it would if it had just been an actual nuclear bomb from the start. Which is to say, very little. But where actual nuclear bombs are guarded by entire armies, this thing was sitting unattended in a basement in hopes that nobody would find the secret elevator button. There are people who keep their collectible Pokemon cards behind more security than that.
And why? Wayne wasn't using the reactor, so why keep it in a functional state at all? Why not just take the pieces apart and store them in different places? Hell, destroy the fucking thing and make sure to keep a copy of the schematics somewhere safe.
Perhaps encrypt them into the Bat-beard.