Factual error: The surviving space shuttle takes off from the asteroid horizontally, like an airliner taking off from a runway. This is absurd. There is no air to provide lift for the wings, so the shuttle - with its engines providing thrust straight back - would simply trundle along the ground like a car. It doesn't use its maneuvering jets at any time, and they are far too feeble to lift the weight of the shuttle anyway. Nor do they gimbal the main engine, which would lift the shuttle vertically on an axis through the centre of the engine - they swoop gracefully into the air after a long take off. Second, they'd have to count on finding a clear length of ground on a debris strewn asteroid. Vertical takeoff, anyone?
Factual error: En route to the asteroid, the two space shuttles head to the Russian space station to refuel. To simulate gravity, the cosmonaut aboard the space station fires a few rockets to put the space station into the spin. How fast does it need to spin to reproduce Earth gravity? Assuming the space station's spoke arms (where the shuttles dock) are about 50 feet long, the answer is 8 revolutions a minute. That makes it impossible to dock - it'd be like trying to drive a car on ice-covered roads into a spinning parking garage. There's another, more fundamental, problem: the artificial gravity points in the wrong direction. Think of spinning rides at the amusement park. The spinning motion creates an artificial gravity, an effective outward-pushing force. On the space station, the spinning would tend to throw the astronauts down the station's spoke arms and back onto the shuttle. Also, the artificial gravity would taper off to nothing at the centre. But the movie's artificial gravity somehow points down, not outward, and appears to work equally well throughout the station.
Factual error: It's explained in detail how the impact will cause a horrible freak tide, what it will do, and that one half of mankind will die in the nuclear winter. That's absolutely irrelevant. The asteroid is "the size of Texas," that means a quarter of a million square miles. Such an impact is called ELE (Extinction Level Event). A bigger part of the Pacific Ocean would evaporate immediately, so no matter if a wave or not. The earth would become "sterilized." So no lifeform will live long enough to die in a winter. (So it is nonsensical to compare that impact with the event 65 million years ago. It's much different).
Factual error: The idea of two spacecraft blasting off together so close to each other at the same time is a joke. One would put the other at great risk. Not only is there massive fire and heat, but the vibrations from the noise of the exhaust do great damage to the surroundings. And there is great inconsistency about just how close the two spacecraft really are. The first still shot taken in the dark has them at different towers about 150 yards apart. But, then all the men take an elevator up ONE tower and are split apart into the two groups at the top of the tower. Furthermore, the launch takes place at Kennedy Space Center Launch Complex 39: the fixed and rotating service structures built for the Space Shuttle are visible. The pads at LC 39 are 8,700 feet apart (just over 1.5 miles).
Factual error: In the Russian space station, A.J. and Lev are running to the Independence shuttle. But as the space station is falling apart, a piece of it crashes into the other end of the hallway they are currently running through. There is no way they would make it to the shuttle even with it being a few feet away; they'd get sucked out into space almost immediately.
Factual error: In the scene with the "lunar roll" (where both shuttles Freedom and Independence are being sling-shot around the moon), they are said to be experiencing "9 and a half G's for 11 minutes". But during this time, the crew members are screaming at the top of their lungs at each other. Under that much pressure it would be nearly impossible to breathe, let alone scream. Even if they're wearing G-suits, with the helmets off, they would be directly exposed to the pressure.
Factual error: In the beginning of the movie, in the scene when the oil well "blows out," pipe starts flying into the air and oil shoots out everywhere. It does not happen like this. When an oil well "blows out" while drilling, the drilling fluid would be the first to come out, followed by the oil. Besides, the crew would shut the blow out 'preventers' long before the fluid would fly out as forceful as in the movie. Also the pipe would not fly out unless no preventive measures were taken. In a subsequent shot, they show one of the roughnecks turning a valve to shut the well in. In real life, the blow out preventers would have to be closed by actuating a hydraulic closure ram.
Factual error: During the teams physicals, the doctor mentions Ketamine. While Ketamine is a sedative it is not strictly an animal sedative. Ketamine is a mid-range sedative that doesn't even put the patient to sleep. I use it in the ER I work in almost every day to set broken bones on children. The good doctor was a bit overly dramatic when describing the drug.
Factual error: Steve Buscemi opens fire with what appears to be a variant of a General Electric GAU-8/A Gatling Gun which has an effective recoil of approximately 10,000 pounds-force (45 kN) per round discharge of armor-piercing ammunition. The vehicle carrying the cannon does not buck upwards or backwards at all. When the significantly decreased gravity of the asteroid is factored into consideration, at the very least the vehicle should have rocketed backwards or flipped upside down! Additionally, the barrels would have been cold-soaked to something close to -273° Celcius when the spinning asteroid was pointed away from the Sun, the heat generated by the rapid fire rate (combined with the friction of the slugs passing through the barrels) would certainly cause the frigid barrels to shatter like glass. And why would NASA fit a Gatling-Gun on a drilling platform in the first place? There are chemical lasers that would be much more effective and certainly lighter in weight should a mission call for the option of blasting one's way through an obstacle.
Factual error: During the movie's opening scene, you watch the asteroid that killed the dinosaurs some 65 million years hitting Earth near the Caribbean (you can see Cuba and Yucatan). 65 million years ago, Earth's continents were in different locations and most of the Caribbean looked very different.
Factual error: In the Paris meteor scene, the POV is from the walkway of Notre Dame cathedral, with a very famous gargoyle in the RH side of the frame. From that POV, the Eiffel tower is visible, but the L'Hôtel national des Invalides (Napoleon's Tomb, the gold-domed building in the foreground) is in the wrong location. To show both of those structures in those positions, Notre Dame would have be located about a mile southwest of its actual location.