Corrected entry: One thousand years after mankind has abandoned earth, despite the abundance of lush foliage, there is a marked absence of oxygen? And if so, it appears that the indigenous wildlife has rapidly adapted to the scarcity.
Correction: It has nothing to do with what we did to Earth. They are both essentially aliens, just like the gravity is different to their home, so is the atmospheric level of various chemicals.
Corrected entry: When the son has been infected by an insect, his father tells him to inject himself with the clear liquid ampoule first, then the other one, but the son is blind, he can't see the difference between the two ampoules. Nevertheless, he injects himself with one, then the other, not knowing if it will work or not, and he doesn't tell his father he can't see.
Correction: You said it yourself, he doesn't tell his father he can't see. So the dad doesn't know, or doesn't know he has gotten to that point yet. The father wouldn't be sure how long ago exactly the boy got bitten nor how long it would take for the poison to react to his particular anatomy. Thus he would be telling him by colors in hopes that he could still see them, and since the son didn't say he couldn't, naturally the father would assume he still could see. As to the son getting it right as far as which one in the right order, was all luck of the draw.
Corrected entry: Throughout the movie, the sword on the kids back appears and disappears from one scene to another.
Correction: No, it does not. Sometimes he is carrying it and sometimes he is wearing it on his back, but it's always with him. Most of the individual shots in this movie do not take place one after the other anyway. After all, it takes less than two hours to show him make a three day journey. So just because it's in one place in one shot and another in the next does not make a continuity error.
Corrected entry: The movie states that every animal/plant on Earth has evolved to kill humans, but humans have not been on Earth for over 1000 years so it would be impossible to evolve to kill humans specifically. Evolution is a process that takes constant interaction and stimulation to occur. It's the essence of trial and error. If they had not evolved before the humans left, then there is no way for them to do it afterwards. (00:29:10)
Correction: You're reading too much into it. He's only saying that every predator on this planet evolved alongside humanity for hundreds of thousands of years and therefore has evolved in such a way as to be capable of killing humans. One thousand years is not that long, evolutionarily speaking. What he means, for instance, is that an alien life form may find the black widow spider's venom to be completely harmless because the black widow did not evolve to be capable of attacking that alien species' nervous system. Nova Prime, the planet humans currently inhabit, likely has many examples of flora and fauna which are venomous to the native species but not to humans. Raige is simply warning his son not to be complacent because that will not be the case here. Also, it's been a thousand years since humanity left Earth; the planet has been mythologized a bit, because obviously not EVERYTHING on the planet has evolved to kill humans SPECIFICALLY even today. Just all the things that can kill are capable of killing humans.
Corrected entry: Nova Prime's sky is full of huge planetary bodies and moons...can you imagine the tidal effects from the gravitational pull of these bodies? The planet would be uninhabitable.
Correction: Although we cannot know how old Nova Prime is as a planet, it can be assumed that it settled into its 'current' habitable state after eons of adjusting to the moons' gravity. When Jaden is running with the Rangers, we can see one very large moon and a smaller one; perhaps the large moon's gravity is enough to make the others insignificant in impacting the planet.
Correction: Will tells Jaden about the oxygen filtration discs, "allowing you to breath more comfortably in the environment". A few images of industrial pollution are shown, suggesting we poisoned the world, which must have included the air, and thus had to leave the planet. If the oxygen levels are simply lower than that which easily support humans, animals could easily have adapted in a thousand years.
DavidRTurner
They are both aliens and simply aren't adapted to the levels of oxygen on Earth.