Actor Allusion: Yzma is voiced by Eartha Kitt, who is well known for portraying one version of Catwoman. She displays an example of To the Batpole! and later gets transformed into a cat. A cute, but still demonic cat.
At one point, Kuzko tricks Pacha into carrying him due to low blood sugar, something David Spade actually suffers from.
Completely Different Title: In Norway, the title is "A Kingdom for a Llama", because the word "groove" doesn't really have a good equivalent. Some merchandise does name it after its original title however (with "style" replacing "groove"), though the former mentioned remains the most known.
The German title translates the same as the Norwegian one, probably because translating the original title would have sounded extremely forced.
The Hungarian title can be rouhgly translated as "Mindless Empire" or "The Empire Gone Crazy".
Cut Song: Just about every song was cut from the movie, except for one, with another played over the end credits. They're still on the soundtrack, though. There's a whole documentary, ''The Sweatbox'', about the film's troubled production (see Troubled Production below) which puts a great deal of focus on these songs (which were written by Sting).
The most notable of which was Yzma's Villain Song, "Snuff Out the Light", which, while a fantastic song, was actually a necessary cut, because the plot of the movie changed and made the motivation and ultimate goal described by the song irrelevant.
Executive Meddling: The film started out as a Prince and Pauper movie called Kingdom of the Sun in 1994, described by Lion King co-director Roger Allers as an "epic picture mixing elements of adventure, comedy, romance and mysticism". It would have been in the traditional style of Aladdin & Beauty and the Beast. The plot would've involved a greedy, selfish emperor who finds a peasant who looks just like him, so the emperor swaps places with the peasant for fun. Meanwhile, the evil witch Yzma has plans to summon the evil god Supai and capture the sun so that she may retain her youth forever. Discovering the switch between the prince and the peasant, Yzma turns the emperor into a llama and threatens to reveal the pauper's identity unless he obeys her. The emperor learns An Aesop about humility, and ends up loving a llama herder named Mata. Together, she & the emperor set out to stop Yzma's evil plans. Sting was signed on as the song composer. Disney execs thought that due to the poor critical & commercial reception of Pocahontas and The Hunchback of Notre Dame, both of which were serious dramatic musicals in the vein of Kingdom of the Sun, the film would be unsuccessful. Compounding this was the fact that the release date had been firmly set at the year 2000, and by 1998 it was clear that production would not wrap up in time. Disney execs ordered production on Sun to be halted. Almost all the original plot points and characters were scrapped. Most of Sting's compositions were cut as well. The movie became transformed into a Looney Tunes-style slapstick buddy comedy. While the end result was warmly received by critics, who found it a breath of fresh air compared to most of Disney's fare, animator Andreas Deja, who supervised animation on Yzma during Sun, was displeased with what the film was reworked into, and left to work on Lilo & Stitch before the retool. Allers was also disappointed with the final film, calling it a "simple slapstick comedy", and saying that if he had had more time, he could've made the film according to his original visions.
On the DVD commentary, director Mark Dindal grumbles about a minor example, claiming an executive at Disney forced him to include a particular The Wizard of OzShout-Out.
Also, Composer Meddling: Sting wrote a letter to the creative team, saying that he was pulling out of the film because the ending had Kuzco building the water park anyway and that entire plot was for naught because the protagonist didn't learn anything from his trials. The producers agreed with Sting's opinion and had the necessary changes made.
There's a rumor that, at one point, the production got so bad that Michael Eisner stormed into a story room, got in the director's face, held his thumb and forefinger an inch apart and yelled "You are THIS close to getting canceled!" before storming out.
Related to Troubled Production: Mrs. "Sting", Trudie Styler, filmed a (slightly unfinished) documentary on the film's production, The Sweatbox. It was screened once, but since Disney owns this document of chaos, they make sure it never gets released (very likely due to there being a large amount of swearing in it), though it was briefly leaked on the internet in March 2012. A review can be found here.
Related to What Could Have Been: Owen Wilson was originally cast as Pachanote who originally was designed to look like a twin of Kuzco...who, by the way, was called "Manco" in the original version. He recorded all his dialogue but when the film was retooled, his voice work was thrown out. There also used to be a short talking Incan statue sidekick to be voiced by Harvey Feinstein. Kronk was nowhere in the story. Yzma's original carnation was creepier, less neurotic, far more threatening, and obsessed with becoming young and beautiful again.
Marc Shaiman originally scored the film but had his work rejected after a test screening and was replaced by John Debney. Shaiman's work can be heard in The Sweatbox (the making-of documentary on the film and its Troubled Production). He describes his take as having too much Mickey Mousing.
The movie as made was supposed to end with Kuzco building his mansion on a hill further away from Pancha's village and inviting Pancha and his family to stay in it, before Sting pointed out that if Kuzco still built his mansion after all his experiences he wouldn't really have learned anything.
Changing the typical Disney Renaissance-era epic into a screwball comedy was nothing but this. It's worth remembering that, at the time this movie was in production, Disney had been doing nothing but epic musical blockbusters, which their staff was gradually becoming sick off and fought against in favor of smaller, more experimental films (this apathy for all that and the lack of adventure films since The Rescuers Down Under hit the breaking point with this and then DreamWorks's Shrek a few months later; Jeffrey Katzenberg's own Writer Revolt and Take That to this genre mixed with the public starting to become tired of it and subsequently crushed the epic musical blockbuster genre until the end of the decade).
A number of the original team, who weren't fired, decided to leave the project during the retool, believing that their work was being trivialized.