The film is based on the life of Milkha Singh. The movie starts from 1960, when Milkha ran in the Olympics and from there the movie goes back to his childhood days during partition. The movie is basically set in the 50s. But in one scene when Milkha Singh visits Pakistan after many years, he is seen driving a Royal Enfield which is a 2012 model.
Similarly in another scene Farhan is seen trying to woo Sonam Kapoor. He sings the song 'Nanha Munha Rahi Hoon' to impress Sonam. However, what is interesting is that the film is based in the 50s while the song 'Nanha Munha' is from the movie 'Son of India' which was released in 1962. So ideally in the scene though Farhan was singing this song, it had not released then hypothetically. In many scenes we could also see mobile towers, but again the movie is set in 1960s and mobile towers were not there then.
During the climax scene where Milkha again wins the race was then known as the Lahore Stadium. But in the movie, the announcer calls it as the Qadafu stadium. However, the stadium was not named Qadafi until 1974. Similarly, the signal on the railway station are electronic, but going by the plot and time-line, electronic systems were discovered much later.
During the race, where a heavily injured Milkha runs and still wins the race is another scene where a major goof up took place. Towards the end of the match, Milkha's dressing comes off but a closer look at his dressing reveals a clean bandage, though Milkha had been running bare foot for so long in the same bandage. In yet another scene, Milkha is released from the jail and his fingerprints are taken on a form. But the date mentioned on the form is of 2013.