During the rehearsals of his transformation scene, Zero Mostel refused to break any of the props, wanting to leave the destruction until he was actually shooting the scene.
The Broadway production of "Rhinoceros" by Eugène Ionesco and translated by Derek Prouse opened at the Longacre Theater in New York City on January 9, 1961 and ran for two hundred forty performances. Zero Mostel's great success in the role of "Jean" (or "John") finally re-established him as a Broadway name following years of blacklisting, although it is actually the smaller of the two leading roles.
Zero Mostel won the 1961 Tony Award for Best Actor in a Play for "Rhinoceros" as John, and re-created his role in this filmed production.
The cane that Zero Mostel carries in the movie is the same wolf-head cane bought by Lon Chaney Jr. as Larry Talbot in L'uomo lupo (1941).
This was first announced in 1967 with Ealing great Alexander Mackendrick set to direct. Peter Sellers and Sir Peter Ustinov were to star, and John Calley was the producer. Unfortunately, the movie did not go ahead. This was one of many Mackendrick projects which failed to materialize.