When Devdas meets Paro in the full moon night, while she was sleeping her black mole keeps changing position.
When Devdas is talking about London, he talks about the Queen's Palace (Rani Ka Mahal), referring to Buckingham Palace. However, the movie is set in the early 1900s and Queen Victoria died in 1901, so he should have called it the King's Palace instead (Raja Ka Mahal).