At two different points, a safety cable can be seen attached to 3 of the actors. Once (at around 1 min) during one of the first expeditions to find the tail of the airplane there are 5 walking. The glacier collapses under the feet of the lead boy, leaving him dangling off the edge of a crevasse. The cable pulls up from the snow just under the actor as Canessa and the others pull him back up. The second time (at around 1h 45 mins) is when Canessa slides off a rock, just as they are reaching the top of the mountain. Nando attaches a safety belt from the Fairchild to his belt and Tin Tin braces himself to lower Nando to Canessa. The thin cable that is hooked to the actor who plays Canessa is partially buried in the snow and pulls up breaking the snow for an instant. You can also see this cable threaded through Nando's left leg of his pants. As the scenes shift, Tintin is sitting on it, and it's also snaked on Nando's left side against the mountain.
The story takes place in the southern hemisphere. However, the sun orientation suggests that they are in the northern hemisphere. Based on what is being described as East and West in the movie, the sun should be slightly to the north during the day, but it's slightly to the south.
The goof items below may give away important plot points.
The day after the avalanche, when one of the boys goes outside through the cabin there is a blizzard there, no sun is visible and he makes just a small hole in a thick layer of snow. But when he returns to the others, bright light shines through the cabin window and casts shadows on walls as if the cabin is open and in broad daylight. A similar scene with another boy is repeated the next day.
At the very end of the film, as the survivors are beginning to hear the helicopters coming to their rescue, there is a reaction shot of Javier (Sam Behrens) where Tintin's shoulder can be seen on the right side of the screen. At this point in the film, Tintin (John Haymes Newton) is wearing a tan vest, which is clear in this shot, and has a full beard. However, the very next reaction shot shows Tintin without the vest with a thin beard. This reaction shot was actually filmed earlier in the movie as part of the scene where the survivors discuss cannibalism for the first time, and is out of place in the rescue scene.
The clothes of the "burnt" victim strapped to its seat headfirst in the snow do not match any of those worn by any of the victims who fell out of the plane after the tail had gone. In reality, these were 5 (4 passengers plus the steward) as depicted correctly in the movie.
Prior to their rescue, the real survivors did learn from radio broadcast that their comrades had been successful in finding help. In the movie, they are cheerfully surprised when the rescue helicopters fly in, obviously unaware of the fact their comrades made it.
It was Roy Harley who received the radio news that the search got called off. In the movie, it's Antonio the captain of the team. Also, it was a guy called Gustavo Nicolich (and not Nando, as depicted in the movie) who then spread the news to the group inside the wreck and suggested they should save themselves.
Although the crash victims were stranded in the mountains for over two months, some of the male characters never grew beards. Ethan Hawke's character, in particular, sported the same well-groomed mustache and small goatee throughout the film. While Ethan Hawke refused to grow a beard, for other characters this is actually correct as some of the younger survivors did not grow much facial hair. Photos taken during the actual rescue show a few of the survivors, such as Roy Harley and Moncho Sabella, with little or no facial hair.
In the scene after the avalanche has occurred, Roy is seen digging for Antonio. Once Roy reveals Antonio's face under the snow, you see Antonio's mouth move, flinching to Roy's touch. Unfortunately, Antonio is dead and shouldn't be able to move at all.