There is a sequence that occurs at Christmas. There is snow on the ground and the characters are dressed for winter. Winter occurs from June to August (approximately) in the countries south from the Equator, like Chile. (Much of the movie was filmed in Denmark.)
The Chilean army of the 1973 is depicted using the wrong equipment such as G3 rifles, M48 tanks, and Fiat G91 aircrafts. The correct weapons would be FAL rifles, M4 Sherman medium tanks, and either Hawker Hunter or F-80 Shooting Star aircrafts.
It's clearly visible that Clara's parents car explodes a little before it hits the train.
The fascist coup in Chile took place on September 11, 1973 which might have been a little early to do Christmas shopping and put up decorations.
Alba is eating KFC, but the KFC name/logo wasn't adopted until the 1990s (it was formerly Kentucky Fried Chicken), it's in a basket instead of a box, and the chain wasn't franchised in South America in the 1970s anyway.