Corrected entry: The cavemen, who previously had no concept of the principles of flight, are taught how to fly a Harrier on a simulator in one afternoon.
Corrected entry: Seeing how the Psychlos have spent centuries conquering Earth in search of gold, how could they not know anything about Fort Knox sooner? Couldn't they have demanded of the humans to reveal the location of this precious mineral?
Corrected entry: Travolta sends Pepper and crew to mine gold. He gives them all the equipment for mining including a working spacecraft. In essence, he is setting a "Batman Trap" by providing them the means of escape. The group waits for Travolta to depart and almost immediately leaves to train and gather weapons. For some reason Travolta doesn't notice that they are flying around the country or doesn't care.
Corrected entry: When Jonnie and the other humans raid Fort Hood, a US Army base, for weapons and supplies, they acquire several caches of weapons, among them Colt 9mm SMGs, evidenced by their undersized magazines and short barrels. The US Army does not field such a weapon, so why would it be in a US Army base? (01:37:00)
Corrected entry: The "cavemen" learn to fly Harrier jets simply from reading the instructions manual. And if this isn't amazing enough, they also manage to perform maneuvers that professional Harrier pilots are not able to perform.
Corrected entry: At the end of the Denver air battle, one of the cavemen (presumably the leader) pursues a Psychlo gunship, and attempts to engage it, but when he runs out of missiles, he gets in position to ram the Harrier into the gunship. Before he crashes into it, he presses the Eject button, yet it doesn't work and he along with the plane slam into the gunship. Strangely, he is seen later during the end scenes, after Psychlo is destroyed. The ejection system was explicitly shown not to work, and even if it did, he wouldn't have been able to clear the plane in time before it impacted the gunship. (01:33:55 - 01:43:55)
Corrected entry: Before the revolt, Ker has a discussion with Terl about the gold that ends in Ker's hand getting shot off. Yet Ker does not scream in pain, nor does any blood gush from the wound. Plus, the wound appears to have been cut with a knife, it is so precise and unlike a gunshot wound. (01:26:25)
Corrected entry: The reason that humans survived the 1000-year rule of the Psychlos was by hiding in the mountains where there was radiation, lethal to Psychlos. Yet, 1000 years on, there is no evidence of genetic defects or cancer in those, something that would be evident living for a long time in an area with background radiation.
Corrected entry: When the revolt begins, Terl orders a Stage 3 Alert, and we are shown Psychlo gas drone ships and troops being prepared to teleport en masse to Earth. Later, when one of the humans teleports to Psychlo to destroy it, the explosion destroys most of the gas drone ships, but one manages to teleport away before the planet is destroyed. That ship is not alluded to by the humans, as it should have appeared on Earth and caused some sort of commotion. (01:41:00 - 01:43:05)
Corrected entry: During the air battle above Denver, one of the cavemen in the Harriers pursues a Psychlo ship attacking his comrade. When he attempts to fire a missile, an alarm in the cockpit blares and a sign saying "Munition Depleted" is shown. It should actually say "Munitions Depleted". The way it is worded in the film implies the Harrier had only one missile. (01:43:40)
Corrected entry: One character says, "Piece of cake" a couple of times in this movie. Why would that phrase have survived 1000 years? Surely none of the characters have ever had cake nor even seen the ingredients needed to bake one. Perhaps "Handful of dirt," or "Dead rat on a stick" would have been more appropriate.
Corrected entry: The Psychlos have been ruling Earth for centuries, yet they still don't know what humans eat?