Chopra died in 2012 and "Gunday" was the last script he had heard.
It was Zafar's idea to include a tribute to the filmmaker, known for directing great movies like "Deewaar", "Kabhi Kabhie" and "Chandni".
Chopra gave his inputs and suggestions to the director regarding the script of "Gunday". He told Zafar to shoot the coal mine scenes at the actual location and not recreate it here, which was also his dream during "Kaala Patthar", said a statement.
"It was Ali Abbas Zafar's idea, he was very, very keen as this was Yashji's last script that he had heard. This was an emotional moment for Ali," said a source from Yash Raj Films, which has produced "Gunday" as well.