The only Peanuts feature film to include adults on-screen and with speaking parts rather than the usual "wa-wa-wa" trombone sound.
The château that Charlie Brown, Linus, and Snoopy stay in is based on the château that Charles M. Schulz was billeted at for six weeks in World War II. This is the Manoir de Malvoisine, near Le Héron. In the film, the estate is called Mal Voisin.
To promote the release of this film (for its May 30th, 1980 release), the May 7th, 1980 episode of The Price is Right (1972) featured a segment from this film. The clip featured was from the sequence aboard the airplane (with Snoopy eating and listening to headphones while hiding Woodstock in the ashtray every time the stewardess walks by). On the showcase featured after the clip, the first item offered is a three piece set of American Tourister luggage. The next item offered is a week-long trip to London. Then, after mentioning that Snoopy visits Wimbledon in the movie, Johnny Olson offers a set of two tennis rackets, with a supply of tennis balls and tennis outfits. Then, mentioning that the Peanuts gang goes to the last leg of their trip in Paris, a week long Paris trip for two is offered. Finally, Olsen notes that in Paris the gang rent a car which Snoopy drives - "being the only one qualified to drive, he takes them on the ride of their lives... and you'll have the ride of *your* life in this new car from France!" - a 1980 LeCar. To top off the showcase, a pass for the contestant and 24 of his/her friends to see a screening of the movie on the Paramount lot was offered. The contestant bid $8,600, the actual retail price was $10,907 and he won when the other contestant overbid on her showcase.