In one of the most hapless marketing tie-in attempts in movie history, Hasbro Toys, in cooperation with Disney, issued a toy version of Flubber, marketed just before Christmas time in 1962. Similar to Silly Putty, in that it could bounce like a ball and make comic imprints, the mixture was a combination of rubber, mineral oil, and green food coloring that had been lab-tested with no ill effects and was marketed as being made of "a new parent-approved material that is non-toxic and will not stain." Within weeks, claims came pouring in to both Hasbro and Disney that the toy Flubber was causing full-body rashes and sore throats in many of the children who used it, resulting in several lawsuits by angry parents. Eventually, after much experimentation, and an intensive investigation by the FDA, it was determined that there was a property in the mixture, of unknown origin, that caused an infection of the hair follicles in certain individuals. The product was recalled, but disposing of it turned out to be an even dicier proposition. Trying to incinerate the mixture only produced a heavy, dense black cloud around the Providence, Rhode Island, garbage dump where the attempt was made. Working with the U.S. Coast Guard to sink the substance at sea turned out to be a fiasco, as well, as the next day almost all of the dumped Flubber came floating back into Narragansett Bay. Finally, it was decided to use the mixture as landfill, buried deep under the parking lot at Hasbro's new warehouse, just outside of Providence. Even then, the incredible but true story doesn't end there. A popular "urban legend" among Hasbro employees is that every year, during the hottest days of summer, you can still spot some of the mixture oozing through the cracks in the parking lot.
Fred MacMurray really was an accomplished saxophone player, so he may be playing the saxophone in the party scene. However this is unlikely as actors were routinely dubbed even if they could play musical instruments. James Stewart was an accomplished accordion player, but all of his playing were rerecorded by a professional for "Night Passage".
Walt Disney abhorred sequels. According to his daughter, he only made the film because there were unused gags from "The Absent-Minded Professor".
Final film of Beverly Wills (mother in Flubber commercial), who tragically perished in a house fire when she was 30.