The scene when the daughter discovers Frank, they get into an altercation which ends with her throwing the nagic cube deal out the window.
He helplessly screams and allows the chick to escape, she scoops up the cube and makes a run for it.
Frank should have just killed the chick and harvested her or whatever. He would have become completely normal looking and could have just strolled out the house, picked up the cube, and continue with whatever plan he had. Would have been a better movie IMO.
ETA: I spoke way too soon, I'm watching it for the first time and it kicks some serious ass.