While Julie Andrews initially turned down the role of Miss Price, she eventually reconsidered, believing she owed her film career to the Disney studio and wanted to work there again. However, when she told the studio she changed her mind, Angela Lansbury had already accepted the part, having signed her contract for the role on Halloween of 1969.
Angela Lansbury hated what she called "by the numbers" acting in this film. Due to the heavy special effects, the entire film had to be storyboarded in advance, shot for shot. It meant every moment was pre-determined and the actress wasn't free to explore the character naturally.
Many people in the film, both on and off screen, have actual connections to WWII. Angela Lansbury, Roddy McDowall, and Robert Stevenson all emigrated to the US from the UK due to the outbreak of war. David Tomlinson served as a Flight Lieutenant in the Royal Air Force. Robert B. Sherman served in the US Army, and was one of the first Allied soldiers to see the Dachau concentration camp. He used his time recuperating from a gunshot wound to the knee to learn about the English people and their culture. Manfred Lating and Fred Hellmich were native-born Germans who had lived under Nazi rule.
While the name of the King of Naboombu is given as Leo in the film, official merchandise guidebooks give his full name as "King Leonidas" (a named derived from lion) after the Spartan king who died at the Battle of Thermopylae in 480 B.C.
The castle in the background of the town is real and situated in Dorset, England. Both the castle and the town where it resides are called Corfe Castle, where many Thomas Hardy adaptations have been filmed since.
Walt Disney bought the film rights to the two Mary Norton books in the early 1960s, around the same time as work on Mary Poppins (1964). When "Poppins" author P.L. Travers stonewalled on the movie rights negotiations to her books, most of the story development along with many of the songs for this film were written at this time. Had Travers not granted the film rights to her own books, Bedknobs and Broomsticks (1971) would have been made instead.
When Disney restored the film as closely as it could to the original cut, it found that not all the original audio tracks for the dialogue survived, requiring the use of ADR for a handful of scenes. Of the original cast, only Angela Lansbury and Roddy McDowall were able to return. Tessie O'Shea died shortly before ADR work began.
Richard M. Sherman and Robert B. Sherman wrote two songs that never made it past preproduction despite Richard's protests. The first, "The Fundamental Element," had Miss Price explain her kindly philosophy to the children after turning Charlie into a rabbit. The second was a Music Hall pastiche called "Solid Citizen," which Miss Price would have sung to distract King Leonidas and get the magic star; ultimately, the soccer game replaced it. Both of them went unheard until demos performed by Richard Sherman appeared on the CD soundtrack reissue. However, part of "The Fundamental Element" was incorporated into the "Don't Let Me Down" portion of "Eglantine."
The film premiered at New York City's Radio City Music Hall. The Music Hall's Christmas stage show ran so long that film premieres had to run less than two hours. After much debate, Disney cut the film down to 117 minutes. After the same thing happened to The Happiest Millionaire (1967) and The One and Only, Genuine, Original Family Band (1968), the Sherman brothers decided not to renew their contract with Disney. In 1995 Scott MacQueen, who headed Disney's restoration department, discovered that two of the cut songs, "With a Flair" and "A Step in the Right Direction", were still on the soundtrack album and quoted throughout the underscore. When he learned the extent of the film's edits, he persuaded Disney to reconstruct the longer cut. Sadly, the picture element of "A Step in the Right Direction" has yet to be located as of the present day.
According to the Laws of the Game, as authorized by the International Football Association Board, no goal should have been awarded during the soccer match. The referee would properly have stopped play at the point where the ball burst or became deflated (Law 2), if not earlier for substandard field surface or goalposts (Law 1), short-sidedness (Law 3), insufficient equipment (Law 4), severe injury (Law 5), advantage gained by being in an offside position (Law 11), or any of various fouls and misconduct (Law 12), including but not limited to: dangerous play, dissent, unsporting behavior, serious foul play, and leaving the field of play without permission.
The trivia items below may give away important plot points.
During the final battle, the bottom half of a knight's armor (from the waist down) is seen with a German soldier apparently seated in the armor with his kicking legs sticking out in front. The actor playing the soldier actually did the walking while two electrically operated kicking special effects legs stuck out in front.
The armor in the climactic battle with the Nazis was authentic medieval armor, previously used in Camelot (1967) and El Cid (1961). When any item of armor was to be destroyed, exact fiberglass replicas were created and used.
The song "Nobody's Problems" was written with two sets of lyrics: one to be sung by the three orphans (which was never recorded or filmed) and the second version performed by Miss Price after Professor Browne leaves. Version 2 was recorded by Angela Lansbury to a piano track by Irwin Kostal, but was cut before the orchestra could be added. 25 years later, an orchestral track was finally added, and when the 25th Anniversary Special Edition premiered at the Academy Awards theater, "Nobody's Problems" received a standing ovation.