Continuity mistake: When Steve Rogers first meets Bruce Banner, Rogers' hair keeps changing between being neat and being blown apart, depending on the angle. (00:32:35)
Continuity mistake: When the Helicarrier is about to take off, Banner and Rogers are still at the edge of the landing strip, identified by the yellow SHIELD logo and the jet that Banner is checking out. But the shot hangs on Romanoff for a second, and when it cuts, Banner and Rogers are instantly at the very edge of the ship, a good 50 feet away from where they were a second ago. (00:32:55)
Continuity mistake: Just after Dr. Banner asks Nick Fury how many spectrometers the Helicarrier has access to, he takes off his jacket, rolls it up, and puts it under his arm. In the next shot, without Banner moving, the jacket is suddenly draped over his arm. (00:34:15)
Continuity mistake: While Loki lies on the floor and talks about the Tesseract, bushes appear/disappear by his left side between shots. (00:43:00)
Continuity mistake: When Thor asks Loki about the Tesseract, he grabs him with his left hand around his neck. The thumb is either by the ear or on the neck, depending on the shot. (00:45:10)
Continuity mistake: When Iron Man and Thor are fighting, Thor grabs Iron Man's wrist at one point. In the next shot, he is holding him by the forearm. (00:46:55)
Continuity mistake: In the beginning of the scene "Mountaintop Battle" while Loki and Thor argue, Iron Man flies into Thor, tossing him to the ground below. Thor's hair is messed up and dirty. The shot changes, and when it goes back to him, he is standing and his hair is clean and neatly combed. (00:47:10)
Continuity mistake: When Thor smashes the hammer against Captain America's shield, they are pushed at least ten feet away from each other. Yet when Iron Man gets up and walks over to Captain America, the two are suddenly much closer together. (00:47:45)
Continuity mistake: In the fight scene between Thor and Iron Man, after Captain America tells Thor to put the hammer down, Thor slaps Iron Man, who is to Thor's right side, back several feet away from them and then jumps even further away. After Thor hits the Captain's shield, as they are all getting up, Iron Man is right next to Captain America and Thor, now to Thor's left side, (when he should be about fifty feet away and still to Thor's right side). Even if Iron Man made it back to Captain America before the shock wave, he should still have been visible before the shock wave for his position on the ground to be possible. (00:49:40)
Continuity mistake: When Thor attacks Captain America and says "You want me to put my hammer down?" Captain America raises his shield, but when the angle changes it's lowered and he's raising it again. (00:49:45)
Continuity mistake: Selvig is carefully moving a cylinder of iridium from a scale to its final location with a metal tongs. The way he holds the tongs changes, when it is highly unlikely that Selvig would change his grip while moving such a delicate substance. Most noticeable are his index and middle fingers. (01:01:20)
Continuity mistake: After Hawkeye fires an arrow at the Helicarrier and part of it explodes, Bruce and Romanoff are knocked out of the room and land on a lower level. As they land, they are shown to be right next to each other, but when they are shown next, the distance between the two has increased by at least two feet. (01:09:45 - 01:10:25)
Continuity mistake: When Hawkeye is breaking onto the Helicarrier, he and some snipers break down a duct cover and enter. When the cover lands on the floor, it is resting away from some pipes with some slats missing. As soon as Hawkeye enters the duct, the cover is now resting against the pipes, and the slats have reappeared. (01:10:35)
Continuity mistake: When Agent Coulson is dying, Fury grabs Coulson's chin with his hand. The hand disappears in the angles shot from behind, only to reappear in the front ones. (01:28:05)
Continuity mistake: Throughout the film, Tony Stark's chest ring can be seen glowing through his shirt except for two occasions when it's suddenly off - after Loki escapes from the helicarrier, and when Loki and Tony Stark are talking in Stark tower, even when he's wearing the same shirt. (01:35:30)
Continuity mistake: After the Chitauri have arrived, Loki stands on the Stark Tower balcony and looks on New York. In this shot, Loki is standing facing the city directly, but by the next shot, he's suddenly standing 90° in the other direction with his head turned to the right, in order to be looking the same way as in the previous shot. (01:39:30)
Continuity mistake: When Captain America, Black Widow and Hawkeye are fighting their way through the Chitauri in the S.H.I.E.L.D. jet, one shot shows the Chitauri blasting at the jet causing part of the front of one side to get blasted and a burn mark is left on the jet. A few seconds later, Loki blasts one of the engines and the burn mark on the front of the jet has vanished. (01:40:35)
Continuity mistake: Sunlight is alternately on the top of Captain America's head or not when he tells the two policemen to get the civilians off the streets. (01:44:50)
Continuity mistake: When Thor says "I have unfinished business with Loki", you can see Hawkeye in the background removing the spent heads of his arrows, four of them, two a little lower then the rest. The shot cuts, and he is holding all four at the same height. (01:46:05)
Continuity mistake: During the battle of New York, Thor has just landed next to an upturned silver car. The rubble around the car changes/moves. The most noticeable is one wedged next to the front right wheel. The piece becomes much bigger in the next shot. (01:50:25)
Answer: While Loki is not immortal, he's just as powerful as Thor, and many mortals would consider him a God as well. Loki is actually a Frost Giant taken in by Odin, but is just as invulnerable to many attacks. There may also be an element of magic involved in his survival as well.
Bishop73