Satyen Kappu dubbed for the main villain' s voice to keep the suspense.
A cover version of the song "Brazil Lalala" (Aquarela Do Brasil) plays during a cabaret dance in the film Gehri Chaal (1973). It was later recreated for Mr Natwarlal in the song "Oonchi Oonchi Baaton Se". It was Mohammed Rafi part " Arrey Hain......" that sounded similar to the part " Braaazil.." One very famous version is. Aquarela do Brazil or Brazil by Ary Barroso.The song would gain major popularity 35 years later when Shakira did her own version.The Venga Boys also sampled the same song for their song "Brazil".
Amitabh Bachchan's picture was no where on the original LP record album released. Only Jeetendra and Hema Malini were on the front cover.
Salim and Javed took Prakash Mehra to Rajkamal Studios where Amitabh was shooting for Gehri Chaal. They wanted to introduce Mehra to Amitabh and show him who they had selected for Zanjeer. Mehra was happy with what he saw and locked in Amitabh for Zanjeer.