This being set in the Eighties, the family drama involves materialism and divorce. Marshall is estranged from Charlie's mother and has thrown himself into his career in retail management. He seems to like the lifestyle of expensive holidays and designer suits and he also has a killer bod. Charlie is small for his age and gets bullied by older/bigger boys.
One morning, as they get ready for the day, Charlie and Marshall have an argument about their lives. This leads to them both wishing to change places with each other, unfortunately while touching the mysterious crystal skull. The room fills with eerie light as Marshall gets smaller and smaller and Charlie goes through a full growth spurt in seconds, leaving them looking like exact duplicates of each other.
Half the film involves their attempts to live each other's lives whilst waiting to fix the change, so 'Charlie' (Marshall) goes to school whilst 'Marshall' Charlie goes to work. The other half involves the attempts of a couple of crooks to steal the skull back.
This movie provides examples of:
- An Aesop: Along the lines of be thankful with what you've got.
- Alliterative Title
- Be Careful What You Wish For: If you don't want to find yourself either miniaturized or suddenly thrust into an adult world for which you've had no preparation.
- Fountain of Youth: 6'2" father Marshall is reduced to a small-for-his age preteen, taking on the form of his son Charlie.
- "Freaky Friday" Flip: Here, the bodies change rather than the minds moving from one body to another. But the outcome is the same — after a change of clothes.
- Gender Bender: Lillian Brookmeyer and her male minion Turk end up in each other's bodies.
- Genre Savvy: At the end, as they prepare to reverse the swap, Charlie (as an adult) instructs his child-sized father to remove his PJs to prevent them being shredded to bits in the ensuing transformation.
- Karmic Transformation: The father is forced to remember how a child's life feels, and the female crook takes on the form of the male minion she abused.
- McGuffin: Ownership of the skull drives the subplot and Failure Is the Only Option keeps the man in a child's body and the child in a man's body until the lesson is learned.
- Mistaken for Prank Call: When Charlie-as-Marshall races to answer the pay phone that one of the kidnappers is calling to, he is breathing so hard on his end for about less than a minute that the female kidnapper thinks it's a pervert on the phone until Charlie-as-Marshall reveals who he is.
- Only Works Once: In the novel. In the movie, they need to work out how they did it, then they can do it again.
- Overnight Age-Up: Wide-eyed preteen Charlie has to deal with the corporate world in the body of Marshall.
- Shapeshifting Excludes Clothing: The film involves a "Freaky Friday" Flip where the father and son changing into each other (rather than their minds changing places), so the two are left wearing their original and now ill-fitting clothes. As they get ready to switch back at the end, they get naked so they won't have to hassle with that again.
- Transferred Transformation: Notably the father and son shapeshift into each other rather than swapping bodies.