Jean-Luc Godard, Anna Karina, Emilienne Caille, Eddie Constantine, Sami Frey, Danièle Delorme, Yves Robert, Alan Scott, Georges de Beauregard and Jean-Claude Brialy all make uncredited cameo appearances as the actors in the silent film shown to Cléo and her friend. In the extras on the Criterion Collection DVD, the movie is called "The Fiancés of the Bridge Mac Donald (1961)".
"5 à 7" is a French expression covering activities carried out after work and before returning home for dinner but it was originally and more specifically a colloquial term for an extramarital affair and for the woman involved (on the basis that the liaisons tended to take place between these hours).
Takes place on a Tuesday afternoon, however the German title translates to "Wednesday from 5 to 7."
Ranked number 2 in BBC Culture's "The 100 greatest films directed by women" list.