Just to clarify some technical details being discussed as plot holes:
Some of these answers arent readily apparent in the theatrical release but the info comes from Cameron via his websites, books , interviews...Would have been nice to have every little detail explained in the movie but it would have been much longer I suppose. I'm sure more details will come out in the sequels and dvd release.
1) Why call it "unobtainium"? Cameron used this classic sci-fi term first coined in the 1950s to refer to any substance that was considered difficult or impossible to acquire. Yes, the name might sound a bit funny to some but its not entirely out of the realm of possibility that somebody would name the mineral that way once it was found (look at the scientific names of some things these days...example: there's the beetle species Colon rectum, first described in 1933). Its not explained in the theatrical release of the film but according to the official websites, books, etc. the unobtainium is the only known high temperature superconductor and is vital to Earth's economy. Fossil fuels have been exhausted and high-efficiency energy systems are critical.
2) Where did Norm go when his Avatar was wounded/killed in the big fight? There was a quick scene, shortly after he crawled out of his link chamber, showing him heading off into the jungle with an assault rifle while wearing his filter mask. Who knows were he went. The shack was parked close to the Tree of Souls so maybe he was heading there to help fight, or maybe he was trying to get away from the bomber heading their way (I'd have parked the shack a bit further away from ground zero i think but thats just me! They wanted to be as close as they could to the center of the flux to remain undetected so there is a reason however) The link chamber that was crushed shortly thereafter by the Colonel was the middle one, right next to Jakes. It was the same one Grace used as a bed when she was wounded. Norm's was at the other end of the shack.
3) How many Na'vi warriors are there? Only a few thousand at the big battle. According to the Colonel's war briefing just before the attack it only took a day for this many to gather. According to Jake this was 15 clans worth. Presumably this would be just the clans in the immediate vicinity. The Colonel was clearly worried about allowing more to show up if he waited to attack. Pandora is a moon yes, but its also nearly the size of Earth (not detailed in the movie but in the background info on the official websites). Why not link and contact everyone? Who knows, maybe they did as well. Certainly Eywa did to gather animals to fight. Still takes a while for people to travel great distances.
4) What happens if you breath the unfiltered air of Pandora? Also as detailed in the official background info, the air is tainted with poisonous carbon monoxide and sulphur dioxide. Thus the need for the exopack filters. According to the sergeants briefing as the shuttle landed, breathing the air unfiltered will cause unconsciousness in 20 seconds and death within a couple of minutes (2?). The Colonel did seem to have a pretty good capacity for holding his breath towards the end. Course none of the characters had immediate problems with atmosphere so long as the vehicle they were in didnt lose a whole windshield at once. Looked like they might have been benefiting from having the cabins partially pressurized.
5) How long did it take to travel to Pandora from Earth? 5 years 8 or 9 months and some days. They didnt go into it in the movie but they apparently have developed real-time commmunication with Earth. According to the official website its expensive, ~$7000/bit of data transfered. So that would be how the production reports, supply requisitions, corporate approvals for spinal repairs, etc go back and forth with out having to wait 12 years for a reply. Might have been nice to have a quick scene involving a data-burst transmission going back and forth...maybe in the dvd release...
6) WHy would the RDA not just nuke the planet and take the mineral? Assuming no humanitarian effort to keep them in check, the RDA would lose its monopoly on Pandora, the neighboring moons and the rest of known space if they use weapons of mass destruction. Official site emphasizes that. RDA is powerful but not the only megacorporation on Earth. Will they be back? I'm pretty sure. We'll see more of em in the next 2 movies that are planned. Unobtainium is too valuable. Will there be further conflict? Almost certainly. According to Cameron, the Na'vi hometrees and other sacred places are usually found on deposits of unobtainium.
7) Why was Jake able to ride a Banshee and the Leonoptryx? Movie said that the animals only flew with one rider for life. It didnt say the rider only flew with the one Banshee his/her whole life.
8) Where did the other Avatar's come from? Well obviously the one Link Center shown at the main base had chambers for 10-12 simultaneously Avatar drivers. There were always drivers entering and exiting their chambers whenever that room was shown, as well as chambers shown closed and in the "engaged" configuration inside their respective alcoves. I counted 12 Avatars outside the base in that scene when Jake runs out for the first time. The end scene shows 3 or 4 of them guarding the shuttle loading (easy to pick em out with their t-shirts, shorts and shoes). Presumably they were off doing the research they were there for, Pandora is a big place. The field shack where the main characters spent alot of the movie was site #26, so its possible there are other similar posts out and about doing what they do.
Yes, there's some things that aren't spelled out in black and white in the movie. I'm a stickler for details so I like to see them. With some movies I can also suspend disbelief enough to appreciate that there are grainy details that are perhaps only hinted at in the background. I imagine some got cut out in interests of time. More will get explained in the sequels. There's something to keeping people asking questions too, and not wrapping everything up in a tight bow. I kind of look at it as this is a brand new world that Cameron created and we'll hopefully get more details as the franchise continues. When Peter Jackson did Lord of the Rings he had the mixed blessing of working with a fairly well known story. That meant he didnt necessarily have to explain every little detail, and certainly not all in the first movie. Of course he did have the challenge of meeting everyone's preconceived expectations of the results. Yes, Avatar certainly has some plot elements that have been done before (Dances with Wolves, Medicine Man, the Aliens franchise,etc) but absolutely original stories are very few and far between if possible at all. The challenge for film makers, authors and other story tellers is to come up with new ways to present familiar story elements in entertaining ways that people can relate to.
