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.
A Rhubarb. It's a donnybrook... a dust-up...
Eric Yeager: Lady, you know what happens at a sale, when two women get hold of the same dress? THAT's a Rhubarb!
Near the beginning of the movie when Rhubarb is being chased by dogs across the golf course, Rhubarb runs into the bushes a golf ball lying on the ground shifts positions (without being touched) one second before the dogs enter the bushes.
The opening cast list ends: "and introducing the newest addition to Hollywood's great galaxy of stars -- that dynamic, exciting, scintillating personality RHUBARB (by special arrangement with the S.P.C.A.) ...A.H.A. Y.M.C.A. U.C.L.A. B.P.O.E. R.F.C.)"