The dog's name in the film is King, and when he becomes human his name is Rex. "Rex" is the Latin word for "king."
According to an article in the 6 April 1951 edition of Variety, Dick Powell was coached on how to act like a dog by Bert Granville, a vaudeville veteran actor who portrayed animals in acts for over 25 years.
The American Airlines plane depicting the arrival of Grandpa Hathaway is a 1940 Douglas DC-3A, registration NC25673. As of 2019 it is still registered as flight-worthy and is owned by the Lone Star Flight Museum in Houston, Texas.
The $6M inheritance would equal nearly $60M in 2019.
Perry's business and flight is to Tulsa, a town star Peggy Dow moved to and lived after retiring.