In the middle of the film, "When the Rain Begins to Fall" of Jermaine Jackson and Pia Zadora is playing in the dancing club. According to the story line, it is before 1981. The song was released in 1984.
In the 70's they go to Étretat in Normandy and use a Leica M7. This camera was released in 2002. Besides, it is one of the most expensive cameras, while the characters just said that they cannot even pay for fixing the toilets in their small apartment.