In no particular order, here are some real facepalm moments.
1# Star Wars- The Exhaust Port
So, the empire wanted to use fear to seize control of an unruly galaxy that was rife with rebellion. For this purpose they created a superweapon, repurposed from a design initially intended for blowing up large asteroids or moons for mining. This weapon was a superlaser mounted on a mobile battle station called the Death Star.
![Posted Image](http://images.wikia.com/starwars/images/7/71/DSI_hdapproach.jpg)
Now, the designers allowed a serious design flaw- an exhaust port, basically a tunnel leading directly from the outside of the ship to its reactor core, wide enough for a pair of photon torpedoes to fit down.
Combined with small gaps in its shields- small enough for fighter craft to slip through... this was a serious mistake.
![Posted Image](http://images.wikia.com/starwars/images/3/31/Protontorpedo.jpg)
Of course, the rebel alliance found out about this, and promptly used x-wing and y-wing fighters to attack it, sending a pair of photon torpedoes down the exhaust port and direct to the reactor.
![Posted Image](http://4.bp.blogspot.com/-BZUpBbJ3KSU/TwCavKj9HLI/AAAAAAAACTg/8Oj00lI_S8o/s1600/death_star_1_destroyed_at_yavin-600x332.jpg)
Now really. A battle station the size of a moon, capable of destroying planets, crewed by many thousands of personnel, and that took a ludicrous amount of resources to build- destroyed just like that by an x-wing.
You have to ask- couldn't they have put a grate over that exhaust port? Or just built a few smaller exhaust ports? put a bend in the port that a missile cant navigate? Maybe the exhaust port was a deliberate act of sabotage in its design process?
2# Starship Troopers Orbital Fleet Tactics
Okay, so in starship troopers, they have an impressive fleet- despite the fact they seem to rely on their infantry for almost everything.
![Posted Image](http://images.wikia.com/starshiptroopers/images/1/15/Vlcsnap-312164.png)
Now, they seem to insist on a fairly close order battle formation for their ships, which does have advantages..... except when carrying out orbital assaults.
When carrying out orbital assaults on two bug planets, they maintained this close formation as they deployed their infantry via dropship- presumably to make it easy for the dropships to all land in the same place... even when the plasma bugs started firing into orbit.
![Posted Image](http://media.comicvine.com/uploads/7/71707/1510061-plasma.jpg)
With the ships in such incredibly close formation, it was a turkey shoot. As ships got hit, they broke up or lost control., and other ships were too close and too slow to maneuvre to avoid ramming into each other.
![Posted Image](http://www.projectorreviews.com/images-articles/InFocus_777_StarshipTroopersShipExplosion.jpg)
So because of their insistence, they took severe casualties, loosing a huge amount of their ships and personel to a bunch of bugs on the ground. Then, they refused to change those tactics.
Also, they deployed their infantry UNSUPPORTED on the ground. They had aircraft, bombers, warships capable of orbital and missile strikes...... and they didn't use these huge advantages. So the infantry got slaughtered.
3# Star Trek- Complete Lunacy.
Its a common scene in star trek- the away team is on a strange world, and BAM! a redshirt dies, whether its by phaser, exotic energy weapon, gun, alien monster, thrown spear, arrow..... all kinds of things.
Now this would be considered a normal risk of doing bussiness... except apparently in the star trek universe personal shield technology is not only capable of preventing these deaths easily, but is commonplace and readily obtainable. Why don't they use these in alot of these episodes? Lazyness? Stupidity? Uncharacteristic Contempt for human life? They want the red shirts to die so Kirk can console and then shag their widows?
![Posted Image](http://www.sitelogicmarketing.com/wp/wp-content/uploads/2007/02/red-shirt-down.jpg)
Also, a running theme in star trek is the following situation- Star trek officer is unarmed in enemy territory. He grapples/fights with an armed enemy. He defeats and disarms said enemy.... and then leaves said enemies weapon lying there instead of arming himself with it.