This film is the only time in animation that Johan appears with dotted eyes, which is based on his comic book appearance. The Hanna-Barbara cartoon series released several years after the film depicted him with larger eyes.
This film was not produced by Hanna-Barbera, the makers of the 1980s Saturday morning TV series The Smurfs (1981). It was originally made in Belgium (the native country of "Smurfs" creator Peyo) by the animation studio Belvision in 1975. The film was brought to the United States by Stuart R. Ross, and his company First Performance Pictures. Ross acquired the North American rights to the film for US$1 million, and produced the dubbed English language version for the US market, with a non-union voice cast who frequently worked on English dubs for Japanese animation. (There was an earlier English dubbed version of this film done for release in the UK, dubbed by British actors.) The rights were then sold to three different American companies: Atlantic Releasing (for the US theatrical release), Tribune Entertainment (for television), and Vestron Video (for home video).
A few years before the US English dub of this film, another English dub was done in the UK. In both dubs, (Sir) Johan was called "(Sir) John" (the Anglicized version of Johan). In the UK dub, Peewit ("Pirlouit" in Belgium; his English name is pronounced "Pee-Wee") was renamed "William," possibly for localization reasons. The villain Torchesac (called Oilycreep" in the translated English version of the comics) is called "Matthew Oily-Creep" in the UK, and "Matthew McCreep" in the US. His associate, Mortaille, whose name in the English-translated comics is "Lord Mumford," retains this name in the UK dub, and is renamed "Earl Flatbroke" in the US dub. The wizard Homnibus is mentioned by name in the UK dub, but remains nameless in the US dub, being called simply "the wizard."
"La flûte à six schtroumpfs" is not the first adaptation of Peyo's "Smurfs" comics, theatrical or otherwise. In the early 1960s, T.V.A. Dupuis produced several black & white animated shorts, adapted faithfully from the comics, for Belgian television. In 1965, 5 of these shorts were collected into a theatrical compilation film titled Les aventures des Schtroumpfs (1965). While the film itself has been scarcely seen since its original release, some of the original TV shorts can be seen on display at the Belgian Comic Strip Center in Brussels.
Despite negative reviews, this film was a major success at the box-office, grossing US$11 million from 432 theaters. At the time, this was the highest on record for a non-Disney film, only to be surpassed by The Care Bears Movie (1985) in 1985. This film was also among Atlantic Releasing's all-time top five movies at the box office, and upon its success, Atlantic established their new (but short-lived) children's film label, Clubhouse Pictures, to release more animated features.
This film was produced under an unusual circumstance: Dupuis Publishing (the publishers of "The Smurfs" comics) produced their own Smurfs animated shorts in the early 1960s under TVA Dupuis, their own animation division. TVA Dupuis wanted to do an original Smurfs animated feature, but at the time, they could only do short cartoons, and was not in capacity of doing a feature-length project, so they approached the animation studio Belvision, owned by Dupuis' rival Le Lombard (the publishers of Hergé's "Tintin," which Belvision adapted into animated TV shows/theatrical movies) to co-produce this film.
Faithful adaptation of Peyo's 9th comic album (graphic novel) starring Johan & Pirlouit: "La Flûte à Six Trous" ("The Flute with Six Holes," later retitled "La Flûte à Six Schtroumpfs"/"The Flute with Six Smurfs," upon the huge success of the Smurfs themselves), featuring some background 'cameos' from characters used in two other albums. The traveling performers at the start of the movie are from book 12: "Le Pays Maudit", while the dog howling in the rain and the two people coming out of the jewelers shop appeared in book 13: "Le Sortilège de Maltrochu".
In keeping with the original Smurf albums by Peyo, Brainy Smurf is repeatedly hit on the head with a hammer (or by a stick) by the other Smurfs to shut him up. This was deemed to violent and too easy to copy by American censors, so in the later Hanna-Barbera cartoon series, he is always catapulted out (either by being tossed out or kicked) of their sight instead.
The reason that Smurfette does not appear in this film adaptation is that the original comic book story this film was based upon was published several years before she made her debut ("La Schtroumpfette"/"The Smurfette") in 1966. Similarly, the evil sorcerer Gargamel (along with his pet cat Azrael) does not appear in this film, because he made his debut in an early story ("Le Voleur de Schtroumpfs"/"The Smurfnapper") in the Smurfs' own comic series in 1959, a year after "The Smurfs and the Magic Flute" (although he did appear in some of T.V.A. Dupuis' B&W animated TV shorts from the early 60s).
In syndicated televised versions of the movie, the Smurfs' party sequence, which originally took place after the completion of the flute and just before Sir Johan and Peewit return back to Homnibus, was shifted to the beginning of the movie, right after the jousting tournament and Peewit's song of friendship, with some narration added.
Jokey Smurf does not appear anywhere in the movie, despite promotional literature and advertisements that say otherwise. Also, the Greedy Smurf that appears in the movie is based on the original comic book version instead of the cartoon series version that wears a chef's hat (which is actually an analog of the original comic book's Baker Smurf character), and is named Sweety. Finally, despite what is illustrated in the movie poster, all the young Smurfs are rather identical in appearance with each other.
One of the taglines on the original US release poster says, "It's the Smurfs' One and Only Full-Length Motion Picture... Ever!" In actuality, it was preceded in Belgium by the 1965 B&W animated compilation film, Les aventures des Schtroumpfs (1965) (which was forgotten and rarely seen since then, having been overshadowed by this film's success in Belgium), and was later followed by the 2011 live-action film, The Smurfs (2011), produced by Sony Pictures Animation.