Two years prior there was a film being made with the same title. R.K.Nayyar Films "Teesra Kaun"(1963). The film was to be made in Hindi and English. Starring Raj Kapoor,Saira Banu,Joy Mukherjee, Music by Shankar Jaikishen, English dialogue - Arjun Dev Rashq, Story and Screenplay -Harish Kumar Mehra, Hindi Dialogues - Agha Jani Kashmeri, Produced and Directed by R.K. Nayyar.
Kalpana stated in the Stardust Magazine September 1982 issue, that she and Feroz Khan fell in love with each other during the making of the film. They were in love and wanted to get married. But her mother turned down the relationship on the basis of religion.
The famous Teesra Kaun chase scene back ground music was used in a scene in the movie CID 909 where Feroz Khan is sitting in a taxi with a sardar cab driver.
The only time Feroz Khan acted with Shashikala.
Feroz Khan and Kalpana fell in love during the making of the film.