Bengali writer director Arvinda Mukherjee wasn't familiar with Hindi so he wrote the script of Amar Prem 1972 in English,writer Ramesh Pant then translated the whole script in Hindi except for the line Pushpa i hate tears.
The film was based on the Bengali film 'Nishipadma' (1970)
Rajesh Khanna, who played the role played by Uttam Kumar, had the name changed from Anata Babu to Anand Babu, to make it more user friendly
RD Burman would go into his room and work from 9 o'clock in the morning till 9 o'clock in the night for Amar Prem.
The song yeh kya hua kaise hua is the true copy of 1970 Bengali movie Rajkumari song yeh ki Holo which was also sung by Kishore Kumar and music by RD Burman