Corrected entry: The movie is set in the 1970's. In the scene where Al Pacino goes somewhere in Broadway to see his ex girlfriend performing and when she meets him at the table where he's siting, she orders a Diet Coke. There was no diet Pepsi or Diet Coke or any other sort of diet soda back in the 1970's. They all came out in the early 1980's.
Corrected entry: They play Patti Labelle's song Lady Marmalade. This isn't right for the time line of 1975 as the song wasn't released until 1982.