This movie is a remake of 2002 Kamal Haasan starer Pammal K. Sambandam (2002). This was not mentioned by the film makers anytime and Kamal Hassan was not credited for the original story.
When Akshay is presenting Kareena with a ring underwater, you can clearly see that the hand on which the ring is put on has short nails. In the very next shot Kareena Kapoor is shown with long nails and pink nail polish. All other scenes before and after she isn't wearing any paint on her nails.