Continuity mistake: When Frank forces Melvin to take in Verdell the dog (just after Simon has been beaten up), the camera follows Verdell as he explores Melvin's apartment alone. Melvin's grand piano at this stage has the lid open, but does not have the music rest up. Shortly afterwards, Melvin re-enters the apartment, prepares food for the dog, places the bowl on the floor in the sitting room, then walks over to sit down at the piano. Suddenly the piano's music rest is up. There is no way Melvin has had the time or opportunity to do this during this sequence.
Continuity mistake: When we see Simon in hospital after being badly beaten up by the thugs, he has long, similar stitches over his face and also over the bridge of his nose. When he is released from hospital most of the cuts have left very visible scars of almost Frankensteinian quality, only the injury on the nose is hardly visible. At the end of the movie, for example when he is talking to his parents over the phone, his nose is now unblemished while the other scars still look quite frightening. (00:30:25 - 01:47:00)
Continuity mistake: When Melvin feeds Verdell for the first time the dog is standing still at the edge of the carpet, facing his dish. When the camera angle changes he is standing further back. Then he lies down, and when the camera angle changes again he is lying at a different spot. (00:28:20)
Continuity mistake: When Simon is explaining to the model how he decides how to paint a person and then tells him to hold it, we see the position the model is in. However, in the very next shot his hand is in a different position it was than when he told him to freeze it. (00:21:10)