Son of Flubber represented the first time that Walt Disney ever attempted a theatrical feature sequel: in this case, the earlier film was the 1961 moneyspinner The Absent-Minded Professor. While Flubber is more formula-bound than Professor, it proved an instant audience-pleaser, and a hit to the tune of nine million dollars. Fred MacMurray returns as professor Ned Brainerd, currently working on his new discovery, "dry rain." The comically destructive side effects of this discovery seemingly doom the professor to failure -- at least until the closing courtroom sequence -- but meanwhile he has better luck with Flubbergas, a byproduct of the antigravity glop he'd invented in the first film. In addition to MacMurray, Absent-Minded Professor alumni Nancy Olson, Keenan Wynn, Tommy Kirk, Leon Ames, Elliott Reid, Alan Carney, Gordon Jones, Forrest Lewis, and James Westerfield reprise their roles from the earlier film, while Ed Wynn shows up in a new guise as a nervous agricultural agent.
~ Hal Erickson, All Movie Guide