Manmohan Desai had a strong dislike for writers Salim and Javed. Alot of the hatred was due to Imman Dharam. They narrated the story of Immaan Dharam to Manmohan Desai and he suggested to producer A.G. Nadiadwala that he buy the story from them . Nadiadwala paid Salim and Javed a huge sum. Then they were offered a even larger price for the script from producer Premji. Salim and Javed returned to Manmohan Desai and told him the script had a defect and they would not be able to develop it further. They requested Manmohan Desai to drop the film. But then Salim and Javed went behind A.G.Nadiadwala's back and developed the story with director Desh Mukherjee. When Manmohan Desai realized what happened, he decided to start a script with the same idea of all three faiths in 1 film . He wanted to show Salim and Javed how angry he was. This was how Amar Akbar Anthony was born.
The hospital scene of Amitabh Bachchan's was not dubbed. This was usually done in most of his emotional scenes.
In the 1970s, producers Tony-Tito gave director Desh Mukherjee a car as a signing amount when his much-hyped multi-starrer Immaan Dharam was in the making. After the film sank at the box-office, the duo had second thoughts. One day, they waylaid Mukherjee who was driving past, and while Tony made conversation with him, Tito drove the car away - leaving the red-faced director stranded in the middle of the road with no car and no future.
This is only one of two films in which Amitabh and Rekha starred but they were not paired opposite each other. The other film being "Namak Haraam" (1973) in which Rekha was paired opposite Rajesh Khanna.
The trio of Amitabh, Shashi and Sanjeev worked together in 3 movies. Imaan Dharam. Trishul. Silsila.