A few months before release, the Disney animators needed Sir Peter Ustinov to come back to the Walt Disney Studios to re-record some of his lines as Prince John. The animators made phone calls to New York City, London, Paris, Vienna, and Tokyo, trying to locate Ustinov, only to discover that he was working at the NBC Studios in Burbank that week, a half-mile down the street from them.
Maid Marian's (Monica Evans') dance with the forest animals in "The Phony King of England" is the same as Snow White's dance with the dwarves in Blanca Nieves y los siete enanos (1937). During the song, she also shares dance movements with Duchess from Los Aristogatos (1970).
Originally, Friar Tuck was to be a pig, but was changed to a badger to avoid insulting religious sensibilities. The Sheriff of Nottingham was originally a goat, but was changed to a wolf as they seem better representing villains.
The famous gap in Terry-Thomas' teeth was incorporated into the design of the character he voices, Sir Hiss (It makes a handy opening for his forked tongue to dart out.)
Because things like backgrounds and characters were so painstakingly drawn and painted by hand, it wasn't uncommon for some scenes and character reactions to be repeated throughout earlier Disney movies.
Wolfgang Reitherman: [re-used animation] During the "Phony King of England" segment in the forest, the illustrators referred to previous Disney films for inspiration. Maid Marian's dance movements are copied from both Blanca Nieves y los siete enanos (1937) and Duchess (Los Aristogatos (1970)). The animals playing the various instruments are lifted almost verbatim from Los Aristogatos (1970). Also, the dance between Little John and Lady Kluck is lifted from the dance between Baloo and King Louie in El libro de la selva (1967). The shot of the animals marching in the parade at the archery contest is identical to the shot of the same animals leading Prince John's carriage in the forest.