Plot hole: Why on earth would the military be interested in a soldier (sailor, aviator, whatever) who has to go into combat naked and unarmed, and who is detectable by an enemy equipped with a pair of cheap, mass-produced goggles? How would you treat them if they were injured? They would be utterly useless in any form of military operation, even espionage.
Plot hole: In the Redstar mainframe, we are told that the floor of the vault will trigger the alarm if it receives more than 0.25 seconds of contact (apparently even with the security checks). What would be the point of the bosses going through all of those security measures if they would just set the alarm off anyway? Surely once the girls have faked the fingerprint and retina scans, they don't then need to flip across the floor! (00:33:55)
Plot hole: The facilities at Ft. Hood have working electricity to power the simulators, projectors, etc. even though it's been 1000 years, with no logical reason for the Psychlos to have kept the facility maintained, and the fact that the Psychlos should by rights have leveled the place when they invaded 1000 years before. Even automatic backup generators would have no fuel after 1000 years dormancy except for a nuclear system, which would still have required regular maintenance over a 1000 year interval to maintain automatic functionality.
Plot hole: It has already been mentioned that a certain shot reveals that Sidney isn't wearing the bullet-proof vest when she should be. Further to this, most of the shots in the climax sequence make it impossible for her to be wearing one, as you can see the contours of her chest throughout. A bullet-proof vest would flatten the appearance of this.
Plot hole: In the first night that Nyah is in Ambrose's house she meets with Ethan outside the house and they talk for about 1 1/2 min. Then we find out "Ethan" was really Ambrose with one of those "high-tech" masks. My question...After being in bed with both, how come Nyah didn't recognise Ambrose is about 5 inches taller than Ethan?
Plot hole: In the makeshift morgue when Simon and Matthew first fight the vampires, Solina is shot and pinned to the wall with a large silver nail and remains calm and unaffected. However, moments later Marcus is fighting with Simon and grabs one of same kind of nails but must drop it when it burns his hands. It makes no sense that Solina had no adverse reaction to the nails at all when Marcus reacted so violently. (00:42:00 - 00:57:50)
Plot hole: After Nanahara and Noriko run away from Akamatsu at the school, Niida shows up from behind some bushes opposite the school and inadvertently kills Akamatsu with his crossbow. But Niida is Boy 16, which means he should still be in the school building (he's supposed to come out after Noriko, who's Girl 15). There's no way he has any time to get into those bushes.
Plot hole: The attack on Israel scene leaves one important question: How would it have been possible for the bad guys (the Russians, or Arabs, or whoever) to stage such a massive surprise attack without being discovered ahead of time? Anyone who is knowledgeable in modern warfare would know that an operation of that scope would require a considerable amount of logistical preparation that could not possibly go unnoticed, especially considering the capabilities of modern spy satellites.
Plot hole: After the marines fire into the crowd and things die down, Jackson tells his men to stay down because of possible snipers. Yet he is standing upright the whole time. Not the best tactical move. One sniper and the mission loses its commanding officer.
Plot hole: When Rudy removes the leg of the bed to escape from the motel room, he finds Charlize Theron and Gary Sinise in the pool. He walks away saying something to the effect of "I am out of here." As he trys to escape, he keeps running into the other members of the gang and has to rush back and pretend he is still handcuffed to the bed when they check on him. If he is already free of the bed, why doesn't he leave after the gang goes to sleep for the night?
Plot hole: How did Carolyn Fry get out of the cave in the canyon to confront Riddick at the Skiff? Riddick strained to roll the rock into the cave entrance, and he was a big, strong man from a position of good leverage. How did Carolyn and the other two push the rock out of the way so that Carolyn could get out? And, then, how did Carolyn mange to push the rock back into place? It was still there when she and Riddick came back from the Skiff to bring back the other two.
Plot hole: In the movie the German sub is in the middle of the Atlantic about 1500 miles from the American coast the American submarine is an S-Class boat which had a top speed on the surface of 12 Knots even less underwater and it spent part of the trip submerged. This means that it would have taken them at least 5 or 6 days to reach the German Sub. This is 1942 There would have been dozens of other German subs a lot closer who could have come to their rescue.
Suggested correction: Presumably the military are interested because Sebastian's research could lead to advanced forms of invisibility technology, such as the ability to turn materials and weapons invisible for use in combat.
You cannot second guess the film like that. Sebastian is making no effort to make non-living items invisible and throughout the film we see that is not possible (why else would Sebastian have to walk about naked?). His research is on animals (and later humans) not "materials and weapons" and is based on their physiology, anatomy and metabolism. How would you inject a rifle or a tank with a serum? They don't have a bloodstream. The military wouldn't see any value at all in this research - maybe they would be interested in invisibility, but not if it was restricted to living creatures as we see here.
You know how easy it would be for an invisible person to infiltrate an enemy's compound undetected and take out powerful leaders or dictators? Especially if no-one knew the technology existed.
Easy? Impossible. First, they would be naked and unarmed. Too bad if you are trying to knock off Vladimir Putin - a taekwondo black belt - with your bare hands during a Moscow winter! Being invisible doesn't mean you can avoid making a sound or triggering a pressure plate or an infrared detector and so on and so on. Final answer - a naked, unarmed combatant would be about as useful as a chocolate teapot in any form of operation, covert or otherwise.