Walter Rilla spoke English with a heavy accent, so his voice was dubbed by another actor.
Although 'buddy Hackett' sang in "The Music Man", he had what could be described as a "funny" singing voice which would have seemed out of place in the eerie "flute-playing" scenes of "The Singing Bone". So his singing was dubbed by Clinton Sundberg, the actor who played the Prime Minister in the film, and who rarely sang onscreen. Although Sundberg did not have a trained singing voice, it had the right gravitas for the somber fairy tale.
In the original version of The Singing Bone, the killer and his victim are a pair of brothers who set out to find and kill a dragon. In the movie version, they were made into a knight and his squire who fight a dragon so as to avoid having Terry-Thomas's character commit fratricide.
Producer George Pal originally wanted Peter Sellers and Alec Guinness to play the Brothers Grimm, but MGM vetoed the idea.
Rumors that 'Wonderful World of the Brothers Grimm' could never be "restored" because the original 3-panel Cinerama camera negatives were heavily water damaged are untrue. Sources close to Warner Brothers and Cinerama Inc, report there is actually very minimal water damage to one edge of one panel in only some reels, and the Technicolor color separation prints are intact for the entire film. Therefore if any of the water damage actually would show on screen or video, that footage could be replaced with new negative made from the Technicolor separations. 3 color separation reels for each of the 3 Cinerama panels means the replacement process would be costly, but not impossible.
Sir Ludwig and Hans were created to somewhat resemble Don Quixote and his squire Sancho Panza.
The second major motion picture filmed in 3-camera Cinerama, although it was released before the first, How the West Was Won.
Turner Classic Movies now shows the full-length version of this film, having added the short prologue, plus Overture, Intermission with Entr'Acte and Exit Music that were not included on the VHS or laserdisc.