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.
At the end of the movie Paul Douglas has a cameo appearance with the line: "A litter from three wives...", a reference to his film A Letter to Three Wives (1949).
At the end of the opening sequence, when Rhubarb is pursuing the fleeing dog past a shop, the film is clearly reversed - the word "Furniture" over the shop front is mirrored, as is the wording on the mailbox.
Eric Yeager: [to Rhubarb]
Now listen ya lug, you're in the chips now, the blue chips. So stop acting like a goon squad. This is an okay dame. She doesn't want a nickel of your dough.