Anachronisms
When Lena and Daniel are driven to the airport near the end of the movie several large buildings show multiple Satelite-Dishes on their roofs - private sat-receivers were not in use in the seventies.
The helicopter landing in the stadium is a MBB BO 105. The military coup took place in 1973, the first BO 105 operating in Chile was built in 1974 (# S-191).
Revealing mistakes
Outside the fence, there's a sign that reads "Keep out". In a country such as Chile, the inscription would be written either bilingual or even solely in Spanish.
Spoilers
Revealing mistakes
Lena and Daniel sit down on auxiliary seats facing the rear of the plane. They don't fasten their seat belts. However after take-off, when the plane goes to a steep climb, they sit comfortably on their seats when they actually should fall off due to the ascent.