Some old Indian movies, specifically Bollywood (Hindi movies), depict several cultural facts incorrectly, including religious customs, roles of women in society, local accents and medical jargon. They also propagate and reinforce incorrect stereotypes about metro cities such as Mumbai and Delhi. Many of these inaccurate depictions continue to be recycled in movies as of 2015, and this often has a profoundly negative effect on real society in unexpected ways.
In old Hindi movies, the followers of a certain religion are depicted as ultra-orthodox, pious people who always follow the rules, while another religion is on the opposite end of the spectrum. The people of this religion are often shown to be promiscuous, godless and ruled by vice. It is also subtly insinuated that anybody following the religion is unpatriotic and therefore not a true Indian.
Female characters are often one-dimensional (there are notable exceptions) and their roles are much more limited than those of male actors. Women who drink and smoke are automatically assumed to be of "loose" character.
In general, old Bollywood films are especially terrible at portraying local Indian accents with any degree of accuracy, and most vernacular roles end up being caricatures and totally unrealistic. Medical depictions of diseases, conditions (autism, stuttering) and treatments are frequently incorrect and probably not verified by professional consultants.
Stereotypes about metro cities are also very common in old movies, creating a huge gap in the understanding of what small town movie-watchers assume to be true and what actually is true.