Trivia

Mumtaz did not want to play the role of Dev Anand's sister and insisted she play the role opposite Dev Anand. Everyone kept telling her that the film was about a brother and sister. Zeenat ended up with the better role causing Mumtaz to be bitter.

During the making of Prem Pujari in Nepal Dev Anand saw a hippie girl puffing a cigarette and got the idea for his next film. HRHK was born. He decided that the girl would be called Jashwin and the story would be based on her. After Prem Pujari becoming a hit, Dev wanted S.D.Burman for the music and his discovery Zaheeda for the role, but both refused. They found HRHK too western. S.D.Burman recommended his son R.D..Burman instead. Dev auditioned Zeenat Aman for the role and the rest is history. The iconic Dum maaro dum was originally not to be there. Dev had told RD and Anand Bakshi the situation of the song. When they created 'Dum maro dum' and made him listen to it, he showed little interest. RD and Anand Bakshi knew that song would be a super hit but since Dev was not interested they insisted he first record 'Dum maro dum ' and they would also give him another song. Dev was very happy to have 'dekho o deewano....' He picturised only half of 'Dum maro dum' on Zeenat and picturised Dekho o deewano' on himself. Singer Usha Uthup got a break but Asha Bhonsle played dirty and snatched it away from her. After this movie Zeenat Aman got several offers to play sister but Dev advised her to reject those offers and made Heera Panna instead where she played his heroine. Due to public demand, Dev Anand was working on the script of Hare Rama Hare Krishna Aaj in 2011 but died before he could complete it.

Dev Anand wanted his children Suneil and Devina to play the younger roles of Prashant and Janice. They were too shy and told their father they were not going to do that.

Zeenat Aman's western culture in the film changed the look of an Hindi cinema actress.

Rappers Method Man and Red Man sampled the song Dum Maaro Dum for their song "Whats happenin".