Against my will, I was just rewatching The Day After Tomorrow and I was blown away again by one scene, where a couple of characters are running away from that most dastardly of villains: PURE COLD! The super-cooled cold struck out its tenacious tentacles at our heroes, following them in an epic CGI chase scene, until our heroes were, in the nick of time, able to get behind a door or something. Take that, COLD! Foiled again! AHAHAHAHAHAHA!
Can you beat that? 
Picking absurdly stupid moments in The Day After Tomorrow is ridiculously easy; part of the film’s charm is that it’s so absurdly stupid. Anyone who knows anything about the geography of Manhattan can point out dozens of stupid and pointless errors.
For instance, the aformentioned cold was established as coming from the north, yet it hits the Manhattan from the south. Or the tidal wave that has to have originated from inland New Jersey. Or the complete disappearance of Long Island even before the tidal wave hits.
The movie assumes Manhattan is on a giant turntable.
I think National Treasure 2 must be in the running.
I need to ask the President of the United States a question that only he can answer! But he must be alone at the time! What ever shall I do? I know, I’ll *kidnap *the President!! How could that possibly not be a good idea? It’s so easy!
Every moment in Flightplan was the stupidest moment in all of film.
I doubt many people noticed it, but during the scene in Terminator 3 where Arnie drives a pickup into Carol’s vet office, collecting the T-X along the way… when the pickup rams through the wall, the film cuts to an aerial shot of the building, and every OTHER square inch of the building bursts into flame - but a five-foot square around the pickup doesn’t explode.
I think you misspelled The Core. 
No. Flightplan was much stupider than The Core. Trust me on this. It was a different kind of stupid, so it’s hard to compare, but Flightplan was truly insulting in the things you were supposed to overlook. It pissed me off in a way The Core didn’t.
Truly it has to be seen to be believed. But it isn’t worth it.
I take it that you haven’t seen 28 Weeks Later yet. The three stooges or the keystone cops couldn’t have done any worse if left in charge than the officials and military in 28 Weeks Later.
How about when Bruce Willis uses his Zippo to light the dripping jet fuel on the ground from the leaking wing of a commercial airliner and it travels like a gunpowder fuse through the air and blows up said commercial airliner lifting off at takeoff velocity?
Oh I’m so glad someone else noticed. It was stupider than anything else I’ve ever seen; the stupidest of stupid films. The only reason I didn’t ask for my money back was because I saw it for free on a ferry to Ireland. God almighty, it was dumber than a bag of rocks that thinks it’s half a bag of pebbles.
My favorite is a different section in Day After Tomorrow when the weather expert decides that the best thing to do when multiple tornadoes are coming at you is to stand in the middle of the road and stare at them.
Too many to name specifically, but one thing that constantly strikes me as dumb, in so many movies is:
Crikey! We’re running away from Bad Guys! Too bad we’re unarmed and vulnerable.
Look out! There’s a Bag Guy! He’s got a gun!
Phew! We overpowered him, and he dropped his gun on the ground.
We’re still running away from Bad Guys. I hope the next one we meet doesn’t have a gun, because we’re still unarmed and vulnerable.
OK, a specific one:
Starship Troopers (yeah, I know). There’s a fucking huge rock hurtling straight at our ship. What should we do? Obviously we should wait until the very last moment before trying to change course.
I dunno, I just assumed there was a reason for that. If the asteroid was tumbling on its axis, maybe turning to early would make it worse, losing half the ship instead of just the communications tower.
Of course, how a slower-than-light asteroid expected to get from “the bug zone” to Earth in anything less than a thousand centuries remains unclear.
The Mission Impossible movies are rich with megadumb. Single worst I can recall offhand is when the team, disguised as firemen, are charging down a hallway at CIA headquarters and one ducks unnoticed into a conveniently unlocked broom closet.
There’s always Independence Day. Do I need to make a list?
As I recall that wasn’t the only major continuity flaw in that sequence but I’m not going back to look at it.
Still doesn’t really make sense - applying thrust earlier means more course deviation.
Guys didn’t you see the way the water tilted in that bit? It’s clear that the asteroid was just a shell around the neutron star the bugs shot at the earth.
Starship Troopers is also good for the many sequences where they clearly demonstrate that the fascists have eliminated OSHA (probably because they’re mustache twirlingly evil) so that workplaces can have things like automatic doors that chop people in half.
Hard to imagine how it could be worse. It’s particularly annoying because in another of his books, Heinlein specifically talks about how easy it is to avoid a (spectacularly unlikely in the first place) space collision – just make any course change early enough. (By the way – this wasn’t the first time this has shown up in science fiction film. This Island Earth has the same thing happening – the space ship has to bank to avoid hitting an object that it should have seen from a zillion miles away. But it looks cool! which is the only point to it.)
Starship Troopers has more tha n enough stupid to go around. Another example is the way the troopers surround the Bugs and keep firing at them in a circle. Even half a second’s thought, even by people unfamiliar with the military and firearms, will tell you why this is a stupid idea – you’re going to hit your own men. And, again, Heinlein himself explicitly states this in the book itself. As i’ve said before, I know of no other movie where the gap between the philosophy, style, and details are so completely at odds between the book and the movie. They have people doing precisely the opposite of what the book says they did, and it makes them seem unbelievably stupid.
To be fair, most movies assume that Manhattan comprises 99.99% of New York.
-Joe