Directed by Cast Member: Both Trey Parker and Issac Hayes (the voice of Chef) have directorial credits on the film.
Dueling Dubs: Two dubs were produced for the Latin American market in 2000, each one by a different ADR studio in Mexico. The version by Sensaciones Sonicas was heavily censored in dialogue to adhere to the standards of local TV, and did not dub any of the songs. An alternate version by Intersound SA (produced for pay-per-view TV) did not soften any of the dialogue, and provided Spanish-language versions of the songs. Although this version was later released on Blu-Ray, the censored version is better known due to its prominence on network TV, as well as having been aired by MTV Latinoamerica and being put up for availability on Netflix.
There are also at least two French adaptations. The mainstream French release did not dub the songs, while a more obscure Quebecois version dubbed all musical numbers. Christophe's nickname was also changed to "The Weasel".
The first dub of the film was released in Hungary in 2000, but became controversial among fans for recasting some of the characters. In 2010, the channel Filmmuzeum commissioned a new dub that would more closely match up with the show's voice cast.
Mean Character, Nice Actor: Mary Kay Bergman, who voiced Sheila Broflovski in what is here arguably the character's most notable role, was very nice in her life, even giving close friend Tara Strong a dog for her 26th birthday (the same year as the movie was released).
Non-Singing Voice: Big Gay Al is usually voiced by Matt Stone, but Trey Parker does his singing voice.
Trey Parker provides Gregory's speaking voice, but his singing voice is actually reserved for Howard McGillin.
In Spain the voice cast was almost completely different from the one used for the TV show. However, Margarita Ponce (the TV voice of Cartman) wound up as Stan's mom for the movie.
The toned-down version aired on Mexican TV kept the voice actors for the four boys and Wendy from the local TV dub of the series, although many supporting characters were recast note In particular, the boys' parents, Chef, Mr. Garrison, Phillip, and Mr. Mackey. Clyde also went from being voiced by a man (Carlos Hugo Hidalgo) to a woman (Isabel Martinon). A less-edited version for pay TV had Kenny and Wendy receive completely different voice actorsnote They were voiced by Irwin Daayan and Maria Fernanda Morales in the TV dub of the movie and the original Audiomaster TV series dub. Their actors in the pay TV dub are Victor Ugarte and Gaby Willert as well as numerous more changes to the supporting cast. Interestingly, the original voice actor for Gregory (Enzo Fortuny) wound up performing the role of Mole in the alternate "dirtier" dub.
The Japanese dub cast is different from that of the show too, with Stan, Kyle, and Kenny voiced by women (as opposed to their TV dub actors) and most of the cast unknown due to the lack of proper credits. The film was also not handled by WOWOW, but by Shochiku Entertainment, who dubbed it for the Kansai market in Japan. As a result, the film contains Japanese subtitles for non-Kansai dialect.
The Brazilian dub of the movie predated a TV adaptation by BVI Communications (and later Kitchen Inc.), and features a completely different cast. While Stan, Kyle, and Cartman are voiced by women in the TV series, they had male voice actors for this version.
George Clooney voices the doctor in the film, while he was voiced by Trey Parker in the series. Although said doctor was also renamed from "Dr. Doctor" to "Dr. Goauche".
Recycled Script: The film is pretty much an extended musical version of the episode "Death" (at least the plot where Sheila tries to shut down Terrance & Phillip due to vulgar content, not the plot of Stan being harassed by his grandfather who wants to die because he's too old to live). Here, Kyle's mom overreacts to Terrance and Phillip and gets the other parents to protest against them (only mass suicide is changed to war).
The film was originally going to open with Saddam getting executed on an electric chair in a gory manner. It got scrapped, but his line "Last words? Let's see, how about, 'GET ME THE FUCK OFF OF THIS CHAIR!'? How's that for last words?" was spoken by Phillip in the final film.
There was originally going to be a music video made for "Eyes of a Child" where Michael MacDonald would be walking on a beach while clips from the movie were projected on a white sheet, but the studio nixed it.
Ike was originally going to follow the boys to the battlefield, as seen in the early trailer footage and promotional screencaps of the film. His role was cut down and he was removed from all later scenes, with the attic scene being added in to explain his absence.
The scene with Winona Ryder was originally going to have her really shoot the ping-pong balls from her vagina, but because the scene would get the film an NC-17 rating, it was changed to a Bait and Switch joke.
The song "Uncle Fucka" was originally plain old "Motherfucker", but again to avoid an NC-17, the song was changed. Trey and Matt admitted the change made the song funnier.
In an early version of the script, Sheila was portrayed a lot less sympathetic and insane. In the 8th draft of the script for the movie, it is clear that the power of leading M.A.C. went to her head and made her insane to the point where after discovering Ike, Cartman, and Kyle were at the USO show, General Plymkin thinks they are "Canadian Sympathizers" and wanted them executed along side with Terrance and Phillip and apparently she and Cartman's mom were okay with it while Stan and Kenny's mothers were shocked at this act. After the war began she went on a insane rant about how perfect her plan is to eliminate "not pretty things" and among other things admitted that Kyle wasn't born in a hospital (It was confirmed in "It's a Jersey Thing"). That and she mistook Satan for Alan Dershowitz. This aspect of Sheila's was dropped from the main film as it seemed to be very uncharacteristic of her and to make her more sympathetic as she saw what the war lead to.
Also, the town of South Park was going to be turned into a concentration camp. While the army does occupy the town, nothing like that happens.
The German scat porn scene with Cartman's mother Liane was originally meant to be a (much shorter) bestiality scene involving a horse. The studio objected despite not being able to see anything on the computer screen. Strangely enough in the finished film, one of the words Cartman said that activated the V-Chip was "horsefucker" and it does show a small image of a man having sex with a horse.
Conan O'Brien originally killed himself via a gunshot to the head, but the MPAA rejected the scene on basis of the gun violence since Columbine and it was switched out with the scene of him jumping and falling to his death.
Originally instead of just Mr. Garrison dying during the war, all of the recurring adult male characters aside from Chef were supposed to have onscreen death scenes (that were filled with punny wordplay).
A subplot in earlier drafts involved Cheesy Poofs being revealed as Canadian and therefore banned, much to Cartman's annoyance.
Kenny was originally given a subplot where he'd have to try to find Snacky S'mores proofs of purchase in order to get a wish granted. In the end, his ghost pressures Cartman to give him some. He then uses them to wish everyone else back to life. In the final product, Satan lets Kenny get a wish granted due to helping him realize that Saddam was a bad partner.
According to composer Marc Shaiman, Sheila's Villain Song was the hardest to write, as over four different songs were written and abandoned. One of them was to have been a dark, sinister Disney Acid Sequence that included a scene where she would scale up a la Maleficent, which was abandoned when he and Trey Parker realized that they didn't want to completely demonize concerned parents, and they came up with a march tune that became "Blame Canada".
The two also fought with Paramount over ways to promote the film. Both were irritated with a music video that the studio had made for MTV for "What Would Brian Boitano Do?", opting to create their own version. Alterations to the film were made as late as two weeks before its release. It has also been stated that Parker and Stone hated the initial theatrical trailer and felt that it misrepresented their intent.