Factual error: When John Ritter and his wife are sitting with the fertility expert, the doctor explains how her reproductive system is not functional. The manner in which he explains this would lead us to believe that she would have been physically unable to menstruate, thus she would have known long before this meeting that she was incapable of bearing a child.
Continuity mistake: At the end of the movie, a car goes off a ramp and is turned upside down. After Jr.'s dad gets shot, watch the tire. It is spinning and a few seconds later it isn't turning anymore. A few seconds later it's turning again.
Continuity mistake: When Jr. is driving with John Ritter on the top of the car, just before they go through the store windows, the cars in the parking lot change significantly from different angles. In one shot a pickup truck is backing out which would block them, but it is gone in the next shot.
Continuity mistake: After Junior's first night at the home, John Ritter tells Junior they're going camping and Junior says he'd rather be watching cartoons. When Junior is speaking his left arm is up behind his head. In the next shot from behind Junior when John Ritter approaches him, the boy's arm is down at his side.