It’s enjoyable to watch this movie about Professor Brainard, a role I've always pictured Robin Williams in, since I first saw the 1997 remake years ago. Fred MacMurray takes on that part here, in the original version. He’s good in it, delivering a performance that is more than adequate—even if it does resemble his work in *‘The Shaggy Dog’* from 1959. Keenan Wynn as Alonzo Hawk also fits the role perfectly. Nancy Olson (Betsy) and Tommy Kirk (Biff) are familiar faces from Disney films, but MacMurray and Wynn really stand out considerably more than everyone else. The special effects haven't held up well over time, but I’m willing to overlook that. The editing is quite abrupt whenever the Flubber is being used; I understand why it is like that, but they could have smoothed those cuts a little bit. What will stick with me most is the humor, which is skillfully written. There are numerous scenes involving the Flubber, and nearly all of them elicit some kind of laughter. Without the fun aspects, I would probably give this a lower rating—particularly considering the ending feels somewhat disconnected from the rest of the film. I do like the remake with Williams better, although it leaves a similar impression as well - largely due to that actor’s exceptional contribution. This is pretty good, though, for a movie full of special effects made in 1961.

Source on TMDB