Corrected entry: When the chief Predator turns the woman's face in the scene where they take the body of the dead Predator on to their ship: He turns the woman's face with his hand to look at the 'tau' mark but we are shown this in visible light where as we all know the Predators can't see for toffee in visible light, so this shot should have been shown through the Predators visible wavelength. But would he have been able to see it in his own wavelength?
Correction: Logically, yes, the Predators must be able to see such a mark. If they couldn't, there wouldn't be any reason for them to use it to mark themselves - what's the point of a mark of honour that can't be seen.
Corrected entry: Icebreakers have round prows, not angled ones.
Correction: Not all icebreakers have rounded prows; there are two main types. The type with a rounded prow slides up on top of the ice and lets its own weight shatter the ice, and the shape of the hull then pushes the ice aside under the remaining ice. The type with a sharp prow have reinforced prows to cut the ice; thicker ice is smashed through by repeatedly ramming it. These types tend to leave more ice fragments behind them than the other type. It should be noted that the shot of the icebreaker's prow in the film was actual documentary stock footage of a real icebreaker.
Corrected entry: There is no explanation as to what initially causes the heat bloom that is detected by the satellite or how this is supposed to lure people to the area when it is presumed that this would be detected even though it is way under ground, and who or what knows that humans have reached the level of technology to detect things from space?
Correction: The heat bloom is caused by the power generators in the pyramid firing up. In case you missed the first two Predator films, the Predators have been visiting Earth on a fairly regular basis to hunt - they could hardly miss the presence of orbital satellites and, with their advanced technology, would be able to figure out their capabilities with ease.
Corrected entry: In the scene where the dead Predator is laid to rest on the slab in the space ship: shouldn't the other Predators be able to see the Alien inside him wriggling about, as they did a few times throughout the film? So therefore they would not have walked off and left him alone.
Correction: They have to intentionally scan the body to see it - it doesn't show up with their normal vision. Apparently they didn't scan their dead comrade - possibly a mistake on their part, but that's a character mistake, not a movie mistake.
Corrected entry: The predators return to Earth every hundred years to train. If this is the case, then surely everyone would know about them, as the story is bound to have been passed down through generations. They say in the film that it was an honour to sacrifice yourself, so that the hunt could begin, so surely there would be some people who would want to continue the tradition?
Correction: When Sebastian tells the story about what he's learned about the Predators and the humans that worshiped them he says "But if the hunters (Predators) lost, they made sure nothing survived", in other words something went wrong and the Predators wiped out everything, killing those who would be able to continue the tradition.
Corrected entry: During the initial briefing, Graeme Miller suggests that if he were given a sample of the pyramid, he could tell how old it is. This has no basis in fact. One could determine how old the stone used to build it is (e.g. 3.2 million years), but not when it was built. If it were that simple, there would be no difficulty in determining the age of the known pyramids today,something that has proved most elusive.
Correction: There are other methods of dating structures that allow accurate dating. Weathering of the stone and knowing where it was mined can help to figure that out.
Corrected entry: When the crew are standing on the ship, their breath is not visible, even though it is supposed to be cold.
Correction: On the ship, they are wearing light clothes, which means that it must have been warm, otherwise they would have been wearing heavier clothes.
Corrected entry: The first Predator is killed by an Alien with a tail that is far too long (at least 30 ft. long, by my estimation) No other Alien in any of the movies has a tail this long, including the queen.
Correction: It could have been a mutation. There's no reason why all Aliens have to be exactly the same. They are not clones.
Corrected entry: The movie states that Aztec calendar (long count) is metric but it is not, it mainly uses base 20 and base 18 (see http://webexhibits.org/calendars/calendar-mayan.htmlAnchor-What-65428). Furthermore, the 'combination lock' and character dialog indicate that the Predators return every 100 years. The concept of a century is relatively modern and not known to Egyptians, Aztecs or Cambodians of ancient times (nor would it fit into their calendar system). Since the movie suggests that the aliens heavily influenced human civilization, one can reasonable assume that the resulting calendars would correspond to Predator traditions. Clearly this is not the case.
Correction: Ok, first of all Aztecs (the ones of the movie) and Mayans (the ones of the website you provided) are two totally different populations. Said this, a year is just the time the planet needs to complete a rotation around his sun so the predator, for some reason, might have decided to come on Earth every 100 'rotations', and a base 20 calendar (like the one you talked about) would fit into this.
Corrected entry: The roof of the Water tank that drags the alien queen to the watery depths breaks open to reveal that the tank is clearly empty (and not filled with oil as a previous correction suggested) Which if it was empty the tank would not sink to the ocean floor but rather float on the surface.
Correction: It definitely would: as the roof is broken, the whole thing would get filled with water and sink in a short time, just like ships do.
Corrected entry: Near the end, Predator and Lex Woods escape the pyramid area via a lift and the Mother alien is just behind them. Seconds after they crash land on the surface, the mother alien is emerging from ice. How can the mother alien travel such a long tunnel within seconds without any lift while the entire pyramid area was getting nuked?
Correction: The Alien queen is ahead of them and has plenty of time to ascend the tube under her own power - it's the other aliens that are behind them.
Corrected entry: It is stated in the movie that the Predators return to Earth every hundred years to hunt. What was the Schwarzenegger fighting in Predator 1 and Danny Glover fighting only a few years later in Predator 2?
Correction: The Predators return to site in the Antartic every 100 years to train the younger Predators, not to hunt. The mature Predators are the ones that hunt and are the ones you see in Predator 1 and 2.
Corrected entry: Why did it take so long for the Alien to burst out of the Predator? One burst out of Adele almost immediately upon her waking but it took about half an hour for it to happen to the Predator.
Correction: As mentioned in another correction, the aliens were genetically engineered for fast "hatching" and growth, with a human host. It is not unthinkable that the predator's different anatomy/biochemistry made it harder for the chestburster to develop inside it.
Corrected entry: When the queen is freed by the other aliens, it looks huge and they are able to crawl all over her. Yet when she runs through the tunnel, she only breaks a bit off the edges, whereas the other aliens can make it through without much room at the edges.
Correction: When the Queen is released she sheds her egg sack, so she loses about 60% of her previous size.
Corrected entry: When Weyland uses his asthma puffer as a flamethrower he is kneeling on flat ground, but when he gets killed he rolls down a row of stairs which weren't there before and are thinner than the original stairs.
Correction: The Predator actually pushes him over the flat area and down the stairs (which where indeed there the whole time) after it kills him. As for the stairs, there is no change in size or thickness.
Corrected entry: When the Predator cuts off the Alien's head and gives it to Lex to use as a shield, why isn't there any acid in the head? There should be at least a little left.
Correction: Actually, the Predator only gives her the skull. The rest of the "internal" parts of the head was removed. This is more clearly shown (explained) in one of the deleted scenes. Besides, without fully knowing the biology of the Aliens, it is safe to assume that there isn't much acid blood in its skull. Clearly shown when one of the other Aliens has its head sliced in half, there wasn't any acidic reaction.
Corrected entry: It is shown the Predators can make metal that the Alien blood can't dissolve. In that case why didn't they make the restraints holding the Queen out of that metal? She was extremely important for the ritual so wouldn't they have used the strongest materials possible?
Correction: There are any number of plausible reasons. The acid-resistant metal may be very rare, so they can't spare enough of it to make the restraints - after all, it's shown that not all the Predator weaponry is made from it, implying that it may be quite uncommon. The possibility of the Queen getting loose may be part of the test, to force the Predators to take a proactive role in hunting down the Aliens before they can get her free. It may even be a simple oversight - honour-obsessed alien killing machines are quite capable of making mistakes.
Corrected entry: The clip that shows the eggs opening & the face hugger moving around is just the same shot being played over & over again. :).
Correction: Um. No, the same shot isn't simply repeated, it's all different shots.
Corrected entry: A whaling station at the location of the movie would have been totally impractical. For six months of the year, during the winter, it would have been uninhabitable. Even now, the permanent bases on Antarctica are cut off completely for about four months of the year. During summer the base would have been extremely difficult to maintain. Even in October a modern ice breaker is needed to reach the island. Whales can't swim under ice, they need oxygen to breathe. So at best the whaling station could have operated for two or maybe three months a year. As far as I know there have never been whaling stations as far south as the movie implies.
Correction: It's possible that the people who built the whaling station misjudged the timing, since this was 100 years ago. It's possible they stayed there waiting for the ice to melt and got caught in the middle of the Alien/Predator conflict. Therefore this is not necissarily a mistake.
Corrected entry: When Grid kills Celtic by shooting his inner teeth/tongue at Celtic's head, you can see it punching a hole through his helmet, right in the middle of the forehead. A second later when Celtic's head falls back lifeless, the forehead is shown and hole is no longer there and the helmet is still intact.
Correction: It's not certain that Grid killed Celtic by punching his tongue through the middle of his helmet. It may have gone through his eye and come out rather close to the middle at the back. This might be the reason why the movie focuses on the reflection of Grid's tongue in Celtic's eyes.