In the beginning when the opening credits roll, a coin can be seen on which there are the following words "Victoria Empress". The events of the film are set in 1857, but Queen Victoria becomes Empress of India by the decision of the British Parliament only in 1876 and this is announced in India in 1877, twenty years after the story of the film. It is important, because the Mughal Emperor (Bahadur Shah II) still alive in 1857 is also shown in the film, and the British Queen gets this title long time after his deposition in 1857 and his death in 1862.
At the beginning of the movie, Mangal has the vermillion mark on his forehead. Later on, while they wait for a new executioner, Mangal sits in the jail cell with no markings on his forehead. Then Heera comes and places the vermillion on him. Since this happens after the initial scene, Mangal's forehead should have been clear in the beginning.