Karen Austin (Sandy Chester) was only 29 when the movie was filmed, and is less than 12 years older than Kerri Green, who played her daughter.
This was one of three John Candy films released during the "Summer" of 1985. The others were Volunteers (1985), where Candy re-teamed with Splash (1983) co-star Tom Hanks, and Brewster's Millions (1985), which starred Richard Pryor.
Summer Rental was filmed in St Pete Beach, FL.
Kerri Green, who played Jennifer Chester, dubbed Aubrey Jene, who portrayed Laurie Chester. As such, both sister characters were voiced by the same actress. Jennifer tells her little sister to "Stop saying everything I say!" One must wonder whether or not that dialogue was included as an inside joke.
In the film, John Candy wears a Chicago Blackhawks sweater with the number 21. The number 21 was worn by longtime Blackhawks great, and Hockey Hall of Famer, Stan Mikita.