Continuity mistake: The first time at the station, Sweetu looks back at the camera representing Aman with a confused look on her face, mouth open a little bit, teeth clenched. During the Heartbeat instrumental song when they show a flashback of the same moment with Aman in the shot, Sweetu looks at him with a big smile on her face. You can see this because when her face turns her mouth is visibly wide open and her lips are curled upward.
Continuity mistake: At the beginning of the song "Kuch To Hua Hai", behind Preity hopping around happily, there is a big sign advertisement for "Toronto Life". The movie is taking place in New York City. Some of the movie was shot in Toronto, but this mistake is just was too obvious to be missed.