The 'but why would they do that, it makes no sense' thread

[Pommygranite]

Following on from this post in the bad films thread it made me think how many times in films there are not only plot holes but plot stupidity:

FourWheelDrift said:

Pacific rim - why did they build giant robots and a giant wall thousands of miles away when they knew where the alien monsters were going to appear, it's like Nelson's fleet being stationed in Alaska in case Boney comes via the North pole. They know where they come through so put a plug in it.

Any others of just sheer 'that makes NO sense' in TV & films?

[Pommygranite]

The Strain - you know the infected have massive alien sucky things and want to kill you but hey, stand there and look stunned when they come near you - take your time, look shocked every time and don't kill them until you've given them a good chnce to attack you.

Every car movie ever - need to win? Well hold your speed, wait for the other car to catch up and THEN change gear and speed off.