Factual error: When you see the blind Syndey walk through her appartment she keeps touching the walls to feel where she is. A person who has been blind for over 20 years (as is mentioned in the film) knows the way around their own home. They know preciseley how many steps it is from room to room. They wouldn't keep touching the wall like this.

Continuity: At the end of the movie, Sydney is playing the violin. They are panning in from the back of her, you can hear her playing, however her bow is not moving. When they show her from the front, she is still playing.