Filmed in chronological order to allow the actors to steadily lose weight to accurately portray the effects of starvation.
The movie depicts the flight crashing on the same day it left Uruguay. In real life, the flight actually had to make an overnight stopover in Mendoza, Argentina, due to bad weather over the Andes. Argentinian law states that a foreign military aircraft is allowed on their soil for only 24 hours, so the pilots had to either return to Uruguay or continue on to Chile. The next day, the pilots decided that although the weather over the Andes was not perfect, it had improved enough to continue on to Chile. This leg of the trip led to the accident.
The director said particular attention was paid to the sound to reproduce the silence and the noises of the snow and high mountain, including conversations with specialised guides used to those climates.
Before the production of this film, the relationship between the survivors, and the families of those who died in the Andes was awkward and complicated. The relatives of the deceased passengers had a tough time dealing with stories about the so-called "miracle of the Andes", focused on the survivors ordeal, but forgetting the ones who were left behind. The production of this film attempted to be very respectful and considerate of those families. Many of the actors who played those who died in the Andes met siblings of their counterparts. Director JA Bayona reunited survivors and relatives as well as families of the deceased at a screening of the film. For many, it was the first time either party had ever spoken to each other about the passengers who didn't make it home.
Some scenes were filmed at the actual crash site in the Andes.