The destruction of New York led to the development of the Manhattan Prison in Escape From New YorkThink about it. With all of the chaos that occurred, the government decides "Screw repairing Manhattan!" and throws the worst offenders in it. After Snake Plissken's little adventure, they finally start fixing things again. (Alan Moore, if you're reading this, feel free to use it in a League of Extraordinary Gentlemen segment).
The aliens are the ones from Watchmen.Veidt made his creations too well, and they punched a hole in space time and came to an Earth without superheroes (save a few with Charles Atlas Superpowers). Lucky for us, he was right about humanity uniting in the face of an incomprehensible evil, and the day was saved, mostly. (The fallout from the nukes — it is likely that other countries used their arsenal on daughterships — the giant UFOs raining from the sky, and the major political and economic centers of each country destroyed, means that we're going right back to Humans Are Bastards a few years down the road.)
The "peace" created by this event didn't last.See the above WMG. Humanity is going to take a long time to recover. We see looting that happened in New York and Los Angeles moments before the UFOs toasted them. A lot of people won't want to wait for civilization to come back.
Alternatively, the peace created by this event is what's necessary to create the first steps towards the United Federation Of Planets.These events aren't mentioned in the archives because it's been a few hundred years and the stories got a little...distorted.
The peace lasted because everybody died right after the creditsThe situation we leave our heroes in as the movie fades to black is even more doomtastic than the Endor Holocaust. A spacecraft "one fourth the size of the Moon" has just blown itself to smithereens; at the altitude we saw it hovering when Goldblum and Smith went to meet it, the debris is pretty much all coming down on us. Even if it was mostly hollow, there will be enough wreckage to bury the surface of Earth several kilometers deep after first incinerating it from the heat of all that junk reentering. Rocks fall, everyone dies.
The city-killer saucers were hydrogen-filled dirigiblesWhy did the aliens use such unreasonably gigantic spacecraft to cart around wimpy beam weapons that packed about as much punch as a pile of nuclear bombs that could fit in a modest-sized human aircraft? Why did the city killers burn so readily when shot with tiny little anti-aircraft missiles once their invulnerable energy shields were down? Why did the wrecked city killer hovering over Area 51 drift gently away to crash far off in the distance? How could they hover without Newton's third law crushing everything on the ground beneath them? Simple — they were almost entirely filled with lighter-than-air hydrogen bladders.
The ships are huge cause the aliens never invented the transistorThe ships are full of giant vacuum tubes.
The Aliens were taken down by the virus because the tech guy had Vulcan helpThink about it. How does a human computer virus, from 1996, take down a space fairing space ship? Easily, he had help from the Vulcans from Star Trek.
The Alien Superweapons were dismantled and reverse-engineered by the army to become Hammerdown.See Cloverfield for more details.
The film takes place during the distant past of the Tengen Toppa Gurren Lagann universeThe reason the aliens strategy involves sucking a planet dry and moving on? They're either running away from the Anti-Spirals, or working to keep the level of Spiral energy in the universe to a minimum so they don't have to worry about their own Spiral energy levels. Their technology would later be used to make the Gunmen.
President Whitman is a Republican.
The Mac Virus worked because...
The alien weapon used to destroy cities is an antimatter containment and delivery systemThe green beams are an antimatter containment system that delivers a small amount of antimatter onto the target. When the antimatter is in place outside the ship's shield, the containment is switched off and a huge explosion occurs. This explains - why the beam is on for some time before the explosion occurs. - how a laser-like beam can transfer enough energy to destroy a city. - why firing into the beams works at the end of the film - this shut down the containment system while the antimatter was too close to the ship and so the ship got blown up instead.
After the end of the movie the remains of the city ships become prime thrill-seeker territory.
Secretary of State Nimzicky was on the alien's side, feeding them information.
The alien mothership runs on the Infinite Improbability Drive.
The Aliens' ships are actually unmanned suicide weapons
In the sequel, the president will have a romance with an alien princess
The movie is actually intended as delivering a Green Aesop.
It is a vicious circle.
Or they took over another star system and thus began FireflyJayne is obviously Major Michell's descendant!
Humans must always fight
Post war Earth is under the rule of a single world state, the Aliens living in District Nine Ghettos.
Postwar Earth, most of humanity is still aliveThe aliens managed to destroy the first set of cities and most of their population because of the small window of time people had to escape. However, they apparently don't get to the next set of cities (which include Chicago and Houston in the Director's Cut) till the next day, giving citizens in most major cities time to escape. In the United States in particular, New York, D.C., LA, Houston, and Chicago are confirmed to be destroyed, but as far as we know Phoenix, either San Francisco or San Diego (depending on which California city the aliens chose to target first after LA), Dallas, and Miami are all probably still intact. Within the USA, Florida might be the best place to live if Miami, Ft. Lauderdale, Orlando, and Tampa are still intact. It's possible also that Canada is doing relatively well. We don't know if the aliens targeted Toronto, but even if Toronto is gone, most of the rest of Canada could still be intact.
Major Mitchell is actually Knowle Rohrer under an alias, or vice versa.Why not? They're both played by Adam Baldwin and it would make some kind of sense given their jobs. Also, when the guy on the phone at the cable-TV-place says "I love the X-Files too", he wasn't referring to the TV show; the guy on the other end of the line was Mulder, whose viewing of some documentary on the paranormal had been interrupted so he was complaining that this would hurt his work on the X-Files. The guy on the phone was just agreeing with him to get him off the line. SO THERE, they can too take place in the same universe.
The list of targeted cities
The ship that attacked Australia was taken down by the wildlife.
The military is okay with the President fighting in the counterattack because it's an election year.First, they need every pilot they can get. Second, if the President dies in the battle but humanity wins, it won't be too much of a problem that there's no President (since the last surviving successor was the Secretary of Defense, who was fired before the battle began, vacating the entire chain of succession), because that condition will only last about six months. They could even have the newly elected Congress pass a law for an emergency transition to have the new President-elect assume office immediately, rather than waiting until January 20. In the meantime, the Chairman of the Joint Chiefs will assume command of the military while the executive powers of the Federal government will devolve on the Governors of the 50 states acting in concert. In fact, due to the crisis, it's likely that special elections to refill the House of Representatives will be scheduled for within a month, at which time they will elect a new Speaker of the House, who would then resign to assume the Presidency. There is a succession plan available, and nobody is going to be starting a war in the aftermath right away, either.
General Grey will be Whitmore's immediate successor as the next President; Capt. Hiller will be the President a few terms laterGeneral Grey was the only person in the government who managed to keep a cool head besides Whitmore himself. He also provided Whitmore with trustworthy advice, in contrast to the sniveling Secretary Nimzicki. By the end of the movie, Grey and Whitmore were basically like Bash Brothers and one can easily imagine that once the 2000 election arrived in-universe, Whitmore would absolutely vouch for Grey and endorse him should he choose to run. Just as importantly, in the aftermath of the crisis, Grey would likely have an Eisenhower-like reputation, and would almost definitely win the 2000 election. Really the only way Grey wouldn't be elected is if he chose not to run, but in the likelihood that America would be faced with many years of rebuilding after the events of the movie, Whitmore would probably urge him to do so, knowing that he's a competent leader who'd command enough popularity and respect to hold the country together during the years of reconstruction that lay ahead. As for the part about Will Smith's Capt. Hiller being President a few terms later, it's basically been confirmed that if Roland Emmerich and Dean Devlin get the go-ahead to make a sequel, this will be the case as long as they can get Will Smith to return.
Post-invasion Europe is dominated by the French-Italian EmpireItaly and France have a huge dose of resentment against anyone who believes them cowards unable to fight, and their relationship tend to be that of Vitriolic Best Friends. Assuming the aliens attacked nuclear powers first due the results of nuking ground troops and lack of knowledge on their ships' ability to survive nukes, France was hit hard but in the end triumphed on their attacker with German, Italian, Portuguese, Spanish and Swiss help... And then most of the world believed it was the everybody but the French and the Italians who did all the job. A few months later Louis, Prince Napoléon is elected Napoleon VI, Emperor of the French and the Italians to serve as a common leader. Immediately after, Switzerland is crushed by the sudden attack coming from East and South, Austria surrender to the Italians when they bomb Vienna, Germany is overran by the French (with the Italians clearing the mountains after they crossed the Alps), Spain and Portugal get spared because they publicly admitted the French and Italian valour from the beginning, the conquered populations are so stunned and terrified by having their armed forces utterly crushed by the military Butt Monkeys of Europe that they join the Empire, and the rest of the world stop making Cheese Eating Surrender Monkey jokes for fear of being next on the list. Then they conquer Libya because Gaddafi tried to get compensations for the Italian occupation and swears when the Empire replies he still owe them money for the nationalized Italian industries, and retake the rest of the Italian colonial empire because Eritrea joins the Empire, Ethiopia tries to stop Eritrea and Somalian pirates mistook the carrier Garibaldi for a tanker and attacked.
The alien ships are powered by broadcast power.That's why all the ships stop working when the mothership goes down, and why they had the one ship for 50 years and couldn't do anything with it. There was no power source on board it for them to reverse engineer. When the fleet showed up, the broadcast power was returned and the captured ship started working again.
Once Earth recovers a bit, the alien ships will eventually be reverse-engineered into our invasion fleet.Then, we set off for some Revenge by Proxy. Alien bastards invaded us without warning? Well, we'll do the same to the first alien scum we find.
If the sequels happen, the destroyed cities will be at least partially rebuiltIf, as theorized above, we reverse-engineer the alien tech, it's not hard to imagine gigantic construction robots being developed to help with the rebuilding efforts.