When Rani Mukherjee lives in Paris, there is a scene in which her mother is watching Teesri Manzil. It's the scene in which Rani is reading and Saif calls her for lunch.
In Hum Tum there are a few references to Before Sunrise during the whole Amsterdam sequence in the starting of the film. The main characters meeting by chance on a flight and then taking a few hours trip of the city Amsterdam and having conversations about relationships, masculine vs. feminine nature, life, etc.