Producer Nasir Hussain approached Dev Anand to star in Teesri Manzil. Dev immediately agreed to work for him. However, at the same time, another of Nasir Hussain's production Baharon Ke Sapne was to be directed by Vijay Anand. Then, on occasion of Sadhana's engagement party, a misunderstanding erupted between Dev Anand and Nasir Hussain, when apparently, Nasir overheard Dev Anand saying "The film which Nasir is making with me is coloured and he has given Goldie some black-and-white film to make. Goldie is making the movie with some new boy, Rajesh Khanna". It was the next day that Nasir requested Vijay Anand to direct Teezri Manzil and specified that Teesri Manzil would not have Dev Anand in it. It was only then that Shammi Kapoor was approached.
The film met massive success and strengthened Shammi Kapoor's career. It also established R D Burman as a trend setting composer.
Producer N C Sippy was to produce the film with Kishore Kumar and Mehmood in the lead roles. The famous character 'Babu Moshai' was to be played by Mehmood. Director Hrishikesh Mukherjee was asked to meet Kishore Kumar to discuss the project. But, Hrishida, was denied entry to Kishore Kumar's house and gatekeeper had the instructions that ' The Bengali' was not to be allowed inside. It is another story, that, 'The Bengali' was someone else abd not Hrishikesh Mukherjee, but, the gatekeeper was not aware of this.
Dejected Hrishida made up his mind to not to work with Kishore Kumar, and so, both of them were dropped from the film. Sippy then considered Sanjeev Kumar for the 'Babu Moshai's' role, but, Rajesh who was now the main lead, refused to work with Sanjeev Kumar.
It was Mehmood, who then, suggested to 'try' Amitabh Bachchan. The rest is history!
Salim Javed's third outing together, Zanjeer was primarily supposed to star Dharmendra in the lead. Prakash Mehra was the director and Dharmendra's brother ajit was the partner in production. However, due to some differences between Ajit and Prakash Mehra, Dharmendra opted out from the film.
Pran suggested the name of Dev Anand. But, this could not go beyond the first meeting with the star. Dev wanted to have a few songs picturised on him. This did not go well with the writers and Prakash Mehra tried to rope in Raj Kumar. Raj agreed to play the lead but he wanted the film to be shot in Madras. He was dropped.
The film finally went to the newbie Amitabh Bachchan. Javed Akhtar was impressed with Amitabh's work in Bombay to Goa. With Zanjeer the Angry Young Man of Indian film industry was born!
The Iconic Gabbar Singh's character was so strong that, even, Amitabh Bachchan and Sanjeev Kumar wanted to play it. The role was offered to Danny Denzongpa, but, he backed out because of his commitement with Firoze Khan for his film Dharmatma.
Upon Salim-Javed's recommendation the role was offered to a new comer Amjad Khan. He was iinitially considered as the weakest link of the film as his voice wasn't as impactful as it should have been. But he played his part very well and is still remembered today for his dialogue delivery.
The roles of two conmen brothers was created for Amitabh Bachchan and Dharmendra. Dharmendra was to play the part of Amitabh. But, Bachchan was a mega star by then and it was a real challenge for the writers, Salim-Javed, to balance the roles. The role, therefore, was offered to Shashi Kapoor and he agreed. Shashi played the part originally meant for Amitabh.
The villain, Shakaal, was a larger than life character and Sippy was confused with the casting. The writers, Salim-Javed once again came to the rescue, and, suggested to meet the new comer, Kulbhushan Kharbanda. Sippy's vision was to create another Gabbar Singh out of a new comer and he signed him.
The film did not do well, but, it was technically more sound than the cult classic Sholay.