Based on a true story. The real Frances Lacey had 12 kids, rather than the 6 portrayed in the film.
When first arriving in Idaho, the Lacey's pass a sign indicating the distance to Hankston and Pocatello Idaho. The Lacey's in the film settle in Hankston, which is a fictitious town. However, the real Lacey family was screenwriter Patrick Duncan's mother and 11 siblings that relocated to Michigan from L.A. after his father was killed.
Norman's red car is a classic 1959 Ford Thunderbird.
The beat up family car is a 1946 Plymouth Special Deluxe.
The classic pink and white sedan is a 1955 Dodge Custom Royal Lancer.