At the height of the film's popularity, "Time" Magazine printed the "Disney" special effects department's recipe for Flubber, as used in the movie. It read as follows: "To one pound of salt water taffy add one heaping tablespoon polyurethane foam, one cake crumbled yeast. Mix till smooth, allow to rise. Then pour into saucepan over one cup cracked rice with one cup water. Add topping of molasses. Boil till lid lifts and says 'Qurlp'." It is not recorded whether this also carried the standard warning "do not try this at home".
Three generations of the Wynn family act in this film: Ed Wynn is the fire chief, his son Keenan Wynn is Alonzo Hawk, and Keenan's son, Ned Wynn is an uncredited actor as a young boy.
The fifth most commercially successful movie at the US domestic box office in 1961, grossing $25,381,407. The most successful was La noche de las narices frías (1961) at $153 million.
Tommy Kirk recalled he was very impressed by how realistic Fred MacMurray's toupees were.
Fred Macmurray was 20 years older than Nancy Olson.