Also, the newscast about Americans crossing the border into Mexico—illegally. Yeah.
Bellisario's Maxim: Emmerich has stated that the film was never intended to be scientifically accurate - the credits claim it was based on the book The Coming Global Superstorm, by Art Bell and Whitney Striber.
Critical Research Failure: There's a reason the main page quote is what it is. This movie's depiction of climatology is accurate in only one technical point; the planet Earth actually does have a climate.
Don't Shoot the Message: While real-life climatologists were glad to see the subject of climate change and global warming getting attention from Hollywood, they've expressed concern that the film's depiction of climate change might desensitize audiences to the reality of the issue.
This is especially troubling to a number of environmentalists as even serious discussions of climate change often go off the deep end in descriptions (claims of the poles melting overnight, our children never seeing snow) when the reality is that it will consist of single-digit changes in average temperature with potentially strong changes in rainfall.
Brian. Helps that he's pretty much one of the only funny characters in this movie.
The homeless man too.
Family-Unfriendly Aesop: The astronaut at the end (after the disaster has destroyed civilization in the northern hemisphere and claimed countless lives) who happily declares that he's never seen the sky so clean. Apparently this is supposed to be the ending's "uplifting" note. Hoo, boy...!
"Funny Aneurysm" Moment / Hilarious in Hindsight: The movie bases its premise on the next Ice Age being caused by global warming. The record cold winter of late '09 / early '10 was pinned on global warming by some climatologists. It's known that global warming can cause a reduction in temperatures in the north, just not anywhere nearly as cold and fast as in the movie.
Depends which end of the political spectrum you're on, but the Vice President's comment about meeting with the head of FEMA as the film was released a year before Hurricane Katrina.
In an eerie real-life coincidence to the film, a reporter covering tornadoes in LA was hit and killed by a flying billboard. A year later, Anderson Cooper was almost decapitated by a flying sign while covering Hurricane Dennis.
It's been debated whether the North American Cold Wave of 2013-2014 was due to climate change (general conclusion: impossible to prove either way but it's a natural event that could have easily happened multiple times in the past without us knowing it), but many of the worst effects were uncomfortably reminiscent of the events depicted in the film.
Even more uncomfortably-so, now that 2014-2015 is seeing Boston buried even worse that Buffalo got it last winter.
And the film's second act; consisting of New York City being flooded by tidal waves has become rather chilling with Hurricane Sandy rolling through the area and causing floods for real.
Tornadoes touched down briefly in Southern California in January 2010.
Hilarious in Hindsight: After disaster strikes, the border between the USA and Mexico is closed and refugees are forcibly turned away. Only it's the Mexicans who have closed the border and are forcibly preventing desperate and destitute Americans from crossing.
Inferred Holocaust: As this video demonstrates, most of the Northern Hemisphere has become an Arctic wasteland, all surviving Americans have gone to Mexico, which won't be able to hold them all, leading to either an American uprising or Martial Law. Canada, Europe, and Russia are all stated or shown to have suffered a similar fate to the one depicted in the US, only worse (because they're further north). Europe is implied to have got hit particularly hard, as south for them would be the Mediterranean, so they were basically trapped. India and China aren't really mentioned but India at least (and parts of China) are probably far south enough the have escaped turning into an ice cube. So that's goodbye Europe (740 million), Russia (130 million), and Canada and most of the USA (call it 250 million?), plus an unknown amount of people in Asia and the victims of all the typhoons and tsunami around the world. It's not (quite) the end of the world, but you're looking at a death toll of at least a billion, possibly closer to 2 billion, with everything north of about 35' latitude now about as hospitable as the North Pole on a bad day.
And then you consider that the above list includes most of the world's core agricultural regions...
Potentially the fate of the astronauts trapped upon the International Space Station, though there are a number of alternate landing sites for the Shuttle, some in the southern hemisphere. Their families, on the other hand...
Hey, our heroes survived just by staying indoors and huddling close to a fire. Who's to say there aren't millions of survivors?
Memetic Mutation: Some people had the balls to claim a screenshot of the flood hitting New York City was an actual picture of what was going on during Hurricane Sandy, leading some people who'd never seen the movie to believe it was real.
Narm: At one point, the characters start trying to outrun the cold weather. Not only that, the cold weather is following them.
Suspiciously Similar Song: The theme when Jake Gyllenhaal and his buddies go inside the Russian ship to look for medicines sounds exactly like the main theme from "Panic Room".
Unintentionally Unsympathetic: A minor point, but showing your work is a standard requirement in virtually all math courses starting in High School. Either Sam didn't bother to check the instructions, or he thought he was such a special snowflake that the rules didn't apply to him.
All the storm effects are incredible, especially the Wall of Water in Manhattan.
The only visual downside in the movie is the CGI wolves which, for the most part, lack detail/complexity in their rendering. But there are still some moments where the wolves look great, such as the shots of them walking/running through the stairs.
Many people over the course of the film. Most notably the Vice President, who dismisses Jack's advice they begin evacuating people, after he witnessed Los Angeles get destroyed by tornados.
Also the French woman that is more concerned about getting her passport than the fact that the streets are flooding and a huge wave is approaching.
And everyone in the library other than Jake Gyllenhaal's character and his friends, who decide to go out in sub zero temperature to look for help. Unsurprisingly they're all frozen to death by the time Jake Gyllenhaal's character's dad comes across their bodies. Made even worse in that they essentially cause the deaths of every child that was in the library along with their parents that left the library.
If you can make it out to the street or the ship, you can make it to other nearby buildings for supplies, helpful survivors, or a better spot to stay warm.