Revealing mistake: Towards the end when Vanilla Ice jumps the motorcycle over Nick's car, you can see the ramp he used through the car's windshield.
Revealing mistake: There are brown pieces of paper that the brother has supposedly been writing songs on (when his sister is in the room cleaning). She picks up the papers and starts to sing, and he flips one of the pieces over as if they have writing on both sides. Only there is no writing on them, even though she is singing the lyrics he has written.