Christmas tree lights

I don't know if this was intentional or just a miss. But the flickering lights looked more like the 90's than early '70s. I am not sure those flickering light were available in 1971. I know this has no influence on the film. Maybe just a small mistake. I liked the movie, but I wouldn't consider it more than it is, a glimpse in the 1971 life, in one spot in Mexico City.