I guess Irrfan has a small but pivotel role. Catch him for a second at 1:20.
As per Wiki, Irrfan Khan plays Dr. Ratha.
Khan described his role as a "pivotal role". Khan also said that he got his role after appearing in the drama tv series In Treatment. He said that Marc Webb has seen his work and approaching him saying he wants to work with Khan.Khan admitted though that he wasn't really interested in the project at first but that both of his sons were excited about it and insisted that he go. The Hollywood Reporter originally reported Khan to play the comic book character, Van Adder.