Auro suffers from a progeria like syndrome. Mentally he is 13 but physically he looks 5 times older. In spite of his condition, Auro is a very happy boy. He lives with his mother Vidya, who is a gynaecologist. Amol is young, progressive politician. He is a man with a mission. Auro is Amol's son. Paa is a 'rare' story about a father-son, son-father relationship.
Acting
Amitabh's childlike physicality through 5 hours of daily makeup.
Practical Effects
The prosthetic transformation that took 4 hours every single day.
Direction
R. Balki making Bollywood's weirdest casting choice actually work.

Director
R. Balki
Trivia, insights & behind the scenes
Amitabh and Abhishek are real father and son; this film had them swap generational roles. The prosthetic makeup was done by Hollywood artist Christien Tinsley, nominated for an Oscar for The Passion of the Christ.
The film is essentially a remake of Francis Ford Coppola's Jack (1996) but with the father-son dynamic added as a uniquely Indian familial layer. Balki wrote it specifically to see Amitabh play 'young' while Abhishek played 'mature.'