So how did the squid/giant facehugger Xenomorph grow so fast without food (energy)? Here's a very simple explanation: Prometheu's crew is listed as 17 in the movie. But if one is to look at the credits, it's apparent that there are indeed 19 passengers. David 8 and Sir Peter Weyland were not counted.
The faith/death of 16/19 crew members is shown and explained onscreen. For example, Fifield kills 5 crew members during his vicious attack.
This leaves 3 members uncounted for. They could not have remained alive on Prometheus before collision. If they were alive, they would have left in escape pods, which were plenty.
So what happened? After Shaw performs a surgery on herself to extract the Xenomorph, she gasses it and leaves the room. Now pay close attention. Her hands are indeed bloody, but she clearly never touches the door, only the keypad.
During the climax, she hears noises and peeks through the window to look into the medical bay and a tentacle slams against the glass. One can now clearly see a half a dozen bloody hand prints on the doors.
Conclusion, the Xenomorph absorbed/ate 3 crew members and that is why it was able to grow so fast and big. Simple as that. These scenes were probably shot and later taken out to keep the lightning fast pacing. All one has to do is think for 2 seconds to realize this. Just because the filmmakers don't show certain scenes, it does not mean that they introduce plot holes, or inconsistencies.
Prometheus is 100% plot hole free. I can gladly explain ANYTHING to anyone. Just ask
**UPDATE 1** (Explanation of finding Engineer establishment on LV-223.)
On a moon the size of LV-223, to find the Engineer settlement, would be the equivalent of locating a specific grain of sand on a beach. But again, it can be easily explained away...
My background is science engineering and my passion is space exploration. I'm an extremely picky viewer when it comes to scientific inconsistencies in movies.
When I judge a Sci-Fi movie I ask two things: Is it plausible, or impossible? If it's even remotely plausible, it gets an automatic pass.
Simply put, the crew got lucky (one in a trillion chance) and were able to find the establishment upon arrival.
But we can also explain it in another way... We clearly see Prometheu's computer performing a booster burn, to get the ship into LV-223's lower orbit. The deceleration causes the pool balls to roll on the table. It apparently stays in this orbit for quite a long time, possibly days. The crew has to be awoken, they have lunch, there's the whole presentation, etc.
What's not to say that Prometheus is not scanning the moon's surface? The starship is obviously equipped with everything it would need to do so, locators, radars, antennas, etc.
We also know that Weyland Industries posses at least some sort of surface scanning technology, the anti-gravity orbs.
The crew might not have know that an actual establishment was there, but they might have picked a more interesting spot from the scan to investigate first.
Upon arrival in this general area, Holloway spots straight lines and the rest is shown on screen.
Sure, they could have taken a minute, or so to explain the surface scanning, but is it really that necessary to stop the narrative for? I would not stop the momentum and I completely agree with the choices the filmmakers made.
Furthermore, the Captain would have to pick a good landing spot ahead of time. The engineers picked that valley for a good reason, to land their huge ships! It's completely logical to assume that Captain Janek has also chosen to land in the same valley, for the same reasons.
**UPDATE 2** (Explanation for radiocarbon dating and DNA matching.)
People seem to have a hard time understanding the DNA matching scene. How can the 9ft. marble skinned engineers be identical to humans? My answer is why not? The DNA was a perfect match to us, humans. Now this DNA can be slightly different, after all, most humans don't share the same exact DNA. But we are all part of the same species. The tallest human is just under 9ft. The shortest is under 2ft. Now think of all the different skin colors, or eye/hair colors, or body shapes, etc. It's perfectly logical to assume that the Engineers share human DNA, just evolved with slightly different traits. They are part of a much older civilization.
The other issue I see being brought up is Shaw's radiocarbon dating. She dates an Engineer's body to be approximately 2000 years old. In order for radiocarbon dating to be accurate, one has to know a lot about the moon/planet, atmosphere, etc.
My simple explanation is that this is a Sci-Fi movie, she had an advanced radiocarbon dating instrument, which she was able to calibrate off screen. How long it took her to do so is irrelevant. It passes the plausibility test.
**UPDATE 3**
The rapid growth of the millipedes (into Xeno hammerpedes/cobra like snakes) after coming into contact with the black goo mutagen from the leaking urns - First of all, the mutagen itself could have been the source of energy for growth and there were entire puddles of it. Second, we were shown a half a dozen millipedes in just one scene. There could have been hundreds of them. Maybe even other small life forms in the dirt. Completely plausible.
Whereabouts of the Xenomorphs that were born from the Engineers 2000 years ago - The dead bodies have their chests burst. The cryo stasis pods have holes which seem to have been blown outwards. The Juggernaut was simply enormous. Same with the temple. The door to get into the ship was sealed, at least from that entrance from the temple's side. But the pilot's room/cockpit lead into many other corridors. It's ridiculous to assume that they should have been found dead right there in the open. 99% of the Juggernaut and the temple was not even explored in the movie, at least not on screen. Most living things, when they die, like to craw into the tiniest of spaces. Remember the ending of Alien and where it hid in the escape ship?
How does Shaw get into the Juggernaut at the end? They don't show it, but it's completely irrelevant. She obviously has an entire climbing/survival kit: Rope, kernmantle ring, pulley, etc. Probably got it from either the tracked ATV, or Vicker's life pod. You mean to tell me that a simple grappling hook was not included? Give me a break!
The Engineer cryo stasis pods had outward burst holes. Apparently some of you think that they are smaller than the baby (Queen?) Xenomorph that was born at the end. I can give you thousands of theories, but here's one: The end Xenomorph was a Queen, while the other ones were regular chestbursters. Simple as that.
What, or why did the Engineer's head burst during re-animation? First of all, no Xenomorph, or any like creature came out of his head. For those who believe otherwise, please watch the scene again carefully. The head bursts, part of the skull flies off, and green mixed with black goo splatters. This matter is not acidic. The Engineers share our DNA, they obviously don't have acid for blood. That Engineer was infected. His veins/arteries were filled with the same black (Nano biological bots?) substance that we later see in Holloway's infection. During re-animation, they put 40 amps of current through the head. The head began to fry, the infection could have accelerated, the nano biological mutagen could have combusted, etc. Pick whatever plausibility makes sense to you
Why did no one witness, or care about Shaw's cesarean? Shaw knocked out Ford and the other technician. I wouldn't follow her either. David and the mercenaries were too busy waking up Sir Peter Weyland. Vickers and Captain Janek were at, or near the bridge. Nearly simultaneously, a good part of the crew had to deal with Fifield's attack.
Weyland most likely ordered David 8 to put Shaw into cryo, during their dream chat. Obviously he would want to take her back home and study her fetus. He then ordered David 8 to wake him up.
Once Shaw performs her surgery and finds David 8 and Weyland, he has already been awoken. The mission's priority is not to go look at what she birthed, it's to go meet our maker. I tend to agree that that's a lot more important.
Now who's to say that the technician Shaw knocks out doesn't eventually stumble to the medpod and get attacked by the Xeno squid? Remember, there are 3 crew members deaths unaccounted for (on screen) in the movie. We later see bloody hand prints on the door. So it's with 100% certainty that the squid got at least one person.
**UPDATE 4**
(My explanation of the opening scene, the sacrifice Engineer's motives and the survivor Engineer's motives)
Let's start by saying that some questions are better left unanswered. Thinking about them is more interesting than having an actual solution presented on screen. Especially if the answers are not interesting. That could ruin the entire movie.
Having said that, in no way did Sir Ridley Scott, Jon Spaihts, or Damon Lindelof cop out. Yes, they leave a lot to the imagination, but they do blatantly answer two of the biggest questions: The Engineers created us (humans) and also the Xenomorphs.
We can assume the beginning takes place on Earth. It's never mentioned, but completely irrelevant. It could have been on any hospitable planet, but it's clear that this is how were seeded.
The Engineers did not seed all life, just us. We can clearly see that there are all sorts of flora and possibly fauna. The opening takes place tens, or hundreds of thousands of years ago, but not billions, when life first appeared.
The sacrifice Engineer gets left behind, he's scared, but proud at the same time. His face says it all. He opens a metallic cup and drinks a biochemical like potion.
Now to seed life, one cannot just leave DNA, or piss in the primodal soup and hope for the best. Whatever he drank, prepped his DNA to spawn new stem cells and create life. The potion is never explained, but it belongs to an incredibly advanced civilization, so anything is plausible.
We don't know anything about the laws, or religious beliefs of this civilization. Because so much life was seeded in the universe, it could have become completely outlawed, or deemed immoral. The saucer Engineers are most likely a rouge religious group who strongly believe in creationism. The biological base on LV-223 could have easily been a military unit assigned to destroy this illegally seeded life. The entire Blade Runner vs. Replicant theme is very evident here.
So why did this Engineer actually have to sacrifice his life, in order to create us in his image? Maybe this group held life and the act of seeding to be extremely noble, important, and sacred. In order to prevent baseless seeding, it was a common and required practice to give a life, for life.
Now whatever happened on LV-223 was obviously a biological accident. Holes in Engineer chests and stasis pods clearly indicate Xenomorphs got lose. The murals tell that the Engineers admired and worshiped their latest creation.
After the accident, what was the surviving Engineer supposed to do? This military unit might not have even been entirely legal to begin with. He can't go back home and bring these monstrous creatures to cause harm to his very own kind. He might have even been infected himself at that point. Going to Earth by himself with a failed experiment makes no sense either. So he puts himself into a long stasis.
It wasn't until the humans invaded LV-223, that left him with no choice, but to go to Earth and destroy them with whatever biochemicals he had.
Captain Janek calls it the way he sees, the Juggernaut is a military ship. It has stockpiles of the deadly mutagen stored in thousands of urns.
So let's talk a little about the contents. The urns are filled with a black liquid. Inside of this liquid are submerged glass ampoules, which contain some sort of nano bot biological content. Both are mutagens and neither are what the sacrifice Engineer consumed at the beginning of the movie. It would make very little sense to infect humans with this potion, as they would just break down and re-seed life via new spawned stem cells, etc. Unless the whole plan was a reset on a global scale, but I find it unlikely.
How do we know that they were going to Earth? The hologram which David 8 activates, clearly shows that their last inputted destination was Earth. It even has a visible outline of the continent of Africa.
The outer black goo is able to cause severe mutations on contact. Fifield becomes nearly unrecognizable after falling into a puddle. The accidentally tracked-in dirt worms by the crew mutate into cobra like snakes. Now the contents within the actual ampoules are slightly different. They seem to have some sort of nano biological bots. They are clearly seen in Holloway's eye, after David 8 infects him.
My theory is that once these urns are dropped on Earth (or any planet/moon) via the Juggernaut. The ampules break open and their nano biological bots come in contact with the black goo and mutate. Together, they either become the Xenomorphs (with a very short built in lifespan) and destroy all life on a targeted planet, or become a super deadly mutagen.
The Fifield attack scene was originally filmed with him morphing into a Xenomorph. I'm glad the filmmakers decided to just make him deformed instead. It would make very little sense for the Engineers to drop the urns on Earth and mutate everyone into Xenomorphs.
