During the big race at the end, listen carefully to when John Candy's youngest daughter asks "Mom, can I play with Yorku?" It's so obviously dubbed and by an adult trying to imitate a five year old girl. Makes me laugh everytime.
When the Barnacle is gaining on the other sailboats, you can clearly see a water jet from the starboard (right) side of the boat, which indicates the engine is running, even though the boat is supposedly under sail.
If you are very observant, when John Candy (Jack Chester) is visiting his neighbor, she proceeds to show him her new breasts. When she lifts her bikini top the scene switches to show her back. But for one split second her breasts are exposed just before the scene changes. Seems like a goof to me.
Contributed by: Marty lawson
When the family is sitting in the living room after being told they will be leaving soon you can see the mom has her hand on her face as John Candy's character gets up and suddenly it's in her lap.