During the middle of the movie when Jack is shown sleeping his hangover off after a night of drinking with Scully, he has an earring in his right ear. However, during the final scene when Jack's boat (the barnacle) is passing Mr Pellet's boat we see a close up of Jacks face in which his earring is in his left ear.
Near the end of the boat race, the Barnacle is supposedly last. Yet, when they pick up speed from the unexpected wind, you can clearly see a boat behind them with a rainbow-colored spinnaker. This may or may not have been the Incisor from "future" scenes in the film.
After kicking out the guy watching the "Smurfs", the cigarettes on the bed change positions between shots while the dog is laying in bed next to them.
When Jack and Bobby meet Scully for the first time to rent a sail boat, there are two boats visibly available. Jack rents the 12 foot smaller boat. When Jack and Bobby set sail by themselves they then have to take an evasive turn to miss the larger rental sail boat now anchored far outside Scullys dock.
After the Barnacle wins the race Don and Gregg give a standing ovation in celebration. Seconds later, as their dog barks, they are seen calmly seated and have switched spots.
When Richard Crenna's character, Al Pellet, buys the house that John Candy's character is renting for the summer he tears up Candy's check and says "I want you and your entire family out by Saturday, Midnight, or else...". When purchasing a property with a renter who has a legal contract, the purchaser of that property is legally obligated to honor all current rental/lease contracts. In this situation Pellet's only option is to honor the summer rental contract. Otherwise, he would be subject to legal action.
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.
From the radio setting on the beach, the weather forecast states that the temperature would reach 105 degrees. It has never reached over 99 degrees recorded temperature in the St Pete, FL area where the movie was filmed.
Early on when Jack is directing aircraft position he says 'Maintain ( or maybe it was descend to) Fifteen Thousand. Proper ATC terminology would be One Five Thousand.
When Jack and family leave home for their trip, several camera angles show there is no dog in the car with them, but after they leave, a very large golden retriever is suddenly in the back seat with the kids.
When asked what she was listening to on her walkman, Jennifer says Wham, but when she takes off the headphones, it's clearly Kenny Loggins, not Wham.
She actually tells him she is listening to "WHAM 104", which is the name of the radio station, not the artist who is performing.
She actually tells him she is listening to "WHAM 104", which is the name of the radio station, not the artist who is performing.
During the first few minutes of the start of the race, there are clear shots of the Barnacle moving from a distance, but close ups of John Candy at the wheel reveal the boat isn't moving at all.
During the Regatta near the end. The Crew are throwing frozen food, and the freezers overboard. This would not only be cause for immediate disqualification in a race but be Highly Illegal you would think, at the very least could be littering. you see other boats witnessing this.
When the regatta race begins, the shots on the Barnacle change to Laurie asking Sandy: "Mommy can I play in the basement with Yorku"? The voice however is not of Laurie, but instead is Jennifer making a young child voice.
(at around 21 mins) When the Gardener family comes to the house in the middle of the night, Jack Chester shows him the receipt for 415 Beach Road. The house turns out to be 415 Beach Lane. An Honest mistake, but the Chester family got into the house by finding a key in the mailbox? It's unlikely the Gardener's would leave a key in the mailbox if they were coming to stay in the house since they had a key to gain entry with them.