"This was for an extended sequence in the film where John is standing on the doors of a running train. Though it seemed like an easy kill on paper, there were complexities that were identified once the whole set-up was being put into place to can the shot," informs a source.
The shot required John to not just bring almost his entire body outside the train, but warranted that John mouth a few dialogues while being oblivious of danger that lay ahead.
"Just capturing the sequence was a nightmare as after every few meters there were pillars right next to the tracks. A few inches more and John's head would have smashed on to the pillars. There was no option to use a duplicate either since the scene had to be captured in one go with John's body and face visible. Time was running out as permissions were for a limited duration," the source continues.
Director Sanjay Gupta was conscious about that as well. He worked with the technical team to make sure that all safety precautions were taken and only when he was completely satisfied did he allow John to get hanging for the shot.
Confirms Gupta, "Yes, John was willing to take the risk and we had put all adequate measures as well to prevent any mishap. But then all of it had to be managed with split second precision. The train was running at a speed of 80 kmph and there was hardly any margin of error. It would be easy on my part to say that it was all a part of the job. However, the truth is that we were terrified. We heaved a sigh of relief once everything went well."