Jean Peters was initially set to star as Ellen Baker. Jeanne Crain was also at one point cast in that role.

Lynn Belvedere is the only character from 'Sitting Pretty' to appear in this film, or the next installment in the series, 'Mr. Belvedere Rings the Bell.'

"Lux Radio Theater" broadcast a 60 minute radio adaptation of the movie on January 16, 1950 with Clifton Webb reprising his film role.

Mr. Belvedere clears the pole vault at a height of 14 feet. That vault would have been good enough for a silver medal at the 1948 Olympics. Due to rain during the finals, the winning vault that year was only 4.3 meters or slightly over 14 feet.

In geometry, a parallelepiped is a three-dimensional figure formed by six parallelograms.

Mr. Belvedere had unusual roommates; Alan Young (Avery Brubaker) would later own a talking horse (Mister Ed (1958)) and Alvin Greenman (Cornelius 'Corny' Whittaker) had been a protege of Kris Kringle (Miracle on 34th Street (1947)).