At the end of the movie Paul Douglas has a cameo appearance with the line: "A litter from three wives.." In reference to the movie A Letter to Three Wives.
At the theatrical opening of this film, kids were handed (for free) an "autographed" picture of Rhubarb. The signature on the photo was a paw print.
Fourteen different cats portrayed Rhubarb at different points in the film. Each cat was trained to do a different trick. Three of the most identical cats appeared in the courtroom scene where Polly Sickles has to choose which one is the real Rhubarb.