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 cavemen, who previously had no concept of the principles of flight, are taught how to fly a Harrier on a simulator in one afternoon.
Correction: They're not cavemen with limited intelligence, they are future humans. They also were given super speed learning via the Psychlos' forced learning machines.
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?
Correction: They conquered the Earth's military in 9 minutes. It's more than possible the remaining humans either wouldn't know anything at all about Ft Knox, or, even if they knew something about it, wouldn't know where it was, or where the gold is stored.
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.
Correction: You just answered your own submission. The Psychlos don't care that humans are running around the country. Humans are nothing more than trained animals to them. In their arrogance, they don't think humans possess enough intelligence to formulate a rebellion.
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)
Correction: The movie doesn't occur in modern time, but in an unspecified future. It's more than possible the weapons could have been stored at Ft Hood sometime during the 1000 years of Psychlo occupation.
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.
Correction: They didn't learn everything from an instruction manual. They practiced in a simulator for 7 days before the final battle.
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)
Correction: There is nothing to indicate the eject button didn't work. The scene cuts immediately after hitting the button, then the shot from outside shows the jet hitting the Psychlo ship. The shot cut quickly, true, but just because we don't see the seat ejecting is no reason to think it failed. Since he does show up during the end scenes, it's safe to assume he ejected safely.
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)
Correction: He doesn't scream because Psychlos have a high tolerance to pain. No blood immediately appears, but we don't know the Psychlo's physiology or how long it may take to bleed. The weapon is an alien technology, we don't know how a wound is "supposed" to appear when a hand is shot off.
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)
Correction: Earth wouldn't have been the only destination the gas drone ships could have teleported to, and seeing as the danger has come from Earth, one solitary drone ship going to the source of the danger wouldn't be wise, therefore it teleported elsewhere.
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)
Correction: Incorrect. The warning refers to ONE type of munition, i.e. the missiles, therefore its grammatically correct for it to be worded as it is.
Corrected entry: Terl and Ker constantly refer to humans as 'stupid man animals'. In fact all of the Psychlos have difficulty in recognizing the 'man animals' of being capable of anything much. So who exactly did they think was responsible for the many buildings and structures still standing, cats?
Correction: First, Psychlos are arrogant beings. That alone explains this. Second, the Psychlos find the humans to be inept in relation to themselves. True enough given the Psychlos level of technology. Even with that in mind, it is glaringly obvious that the humans inhabiting the present world are no where near as technologically capable as those who inhabited the world when the Psychlos first arrived. This is more of a plot *point* than a plot hole. At any rate, it's certainly not a movie mistake.
Corrected entry: The Psychlos have been ruling Earth for centuries, yet they still don't know what humans eat?
Correction: They don't care. Being technologically advanced does not necessarily imply actual intelligence. You might say their race is on the downward curve in their intellectual evolution. Look at the human race: All of the technology we've got and many of us couldn't figure out how to keep ourselves alive without it for more than a week.
This is still confusing enough, thus making it a mistake. Even if they didn't care they would have learned it unintentionally.
Correction: Most Psychlos don't care at all what humans WANT to eat. They care about what humans NEED to eat, i.e. humans doing hard labor needs X many calories to survive and must have at least Y protein, Z fat, etc... Terl is trying to essentially bribe Johnny with something even lower animals can appreciate: a favorite treat.
Correction: It is a normal movie convention to use terminology which the viewing audience understands, even if it might be factually incorrect. The audience of today would have no clue what was meant by "Handful of dirt" or "Dead rat on a stick". Therefore the term "Piece of cake" is used for our benefit and is not a mistake. (See similar corrections for movies such as "Troy" and "Pirates of the Caribbean" for comparison).