The aircraft reflected in the water at the beginning is an Airbus 340, which was released for commercial use in 1993. There is also a Boeing 767 seen landing near the martial art field which was launched in the early 80s.
The end of the film takes place in 1971, but Señora Sofía pulls into the driveway in a new Renault compact with a front grill badge logo designed by Op-Art originator Victor Vasarely that was not introduced until the following year, 1972.
On the scene previous to the attack on the students, the camera travels along several military vehicles, many of them bearing a very contemporary FORD logo on the radiator screen. then slows to show a VW Safari from the right era.
The children are shown in late 1970 watching a television program in which Master Zovak is using using his teeth to pull a car that's attached to a chain. The car is a VW Safari. However, civilian sales of the VW Safari didn't begin in Mexico until later in 1971.
Throughout the movie we are told that the husband is in Quebec. Towards the end when they go to the Playa and are having dinner, the mother tells the children that he was never in Ottawa. Ottawa is in Ontario and not in Quebec.