Defictionalization: The whole thing! More specifically, it's a defictionalized Diagon Alley, Knockturne Alley and Hogsmeade, with almost all the shops from those locations (Ollivander's, Borgin and Burke's, Honeydukes, the Leaky Cauldron, etc.) being available to you—the few that aren't, such as "Potage's Cauldron Shop" and "Eeylops Owl Emporium" are presumably removed due to having a limited selection of items to sell—and they even insert little tiny details as well, such as Moaning Myrtle's voice in Hogsmeade's bathrooms and Kreacher peeking out a window in Grimmauld Place. Additionally, the park also put lyrics to Celestina Warbeck's songs, which were only ever alluded to in the books.
Demand Overload: When the ride and the surrounding area first opened, lines just to get into the area were so long that they went outside the park and circled around CityWalk. News reporters had quite the field day.
Executive Meddling: Though Universal Creative is responsible for the park's design, it is well known that Warner Brothers and J.K. Rowling both hold a powerful veto over just about every aspect of the land.
The Dark Arts event, which sees numerous unique special effects added to Hogsmeade alongside Death Eaters roaming the land, nearly always occurs alongside Halloween Horror Nights. For years however, a Warner Bros. mandate forbade Universal from referring to or promoting Dark Arts as a Horror Nights event, as well as using associated language such as "scarezone" to describe it. The mandate was loosened in 2023, allowing Universal to explicitly market the appearance of Death Eaters roaming Diagon Alley as a Horror Nights event.
The Merch: The Magical Menagerie sells stuffed animals of many of the magical creatures from the franchise. Weasley's Wizard Wheezes sells plush Pygmy Puffs and even gives a little naming ceremony for the ones that get "adopted". Owl Post sells stuffed owls along with post cards.
No Export for You: Diagon Alley is exclusive to Universal Studios Florida.
The Other Darrin: Though they reprised their roles for the Forbidden Journey attraction, neither Daniel Radcliffe and Emma Watson were interested in reprising their roles any further, so in both Escape from Gringotts and Hogwarts Express, they're replaced by reused footage and dubbed by two unknown actors.
Sequel Gap: It took six years after the Orlando location opened for Hollywood to receive their own version of the area.
Troubled Production: As mentioned below, J.K. Rowling originally wanted Disney to develop a Harry Potter area, but after numerous disagreements she reluctantly went to Universal to do the job.
J.K. Rowling and Warner Bros. originally intended to sell the theme park rights to Disney, including a letter of intent in 2004. However, by the end of that year, talks had broken down for good. Rowling and WB wanted to make the land very immersive (including no outside brands or character meet and greets) but all Disney was willing to give was a section of their intended Fantasyland expansion with one ride, a gift shop, and restaurant. They had never developed a land devoted to a single IP at that point. Disney also wanted to stick exclusively to the books to not advertise a rival studio’s franchise which Rowling and WB weren’t willing to do. The ride would've involved guests using wands and firing at interactive 3D screens (this concept later became the basis for Toy Story Midway Mania!). You can imagine why Rowling and WB went to Universal instead.
Plans for Harry Potter at Universal go all the way back to 1999 when it was originally envisioned as a stunt show attraction.
Early concept art shows a far less ambitious version of the area, that would've not included a Hogsmeade and would've retained much of the Lost Continent's theming, including the Enchanted Oak Tavern restaurant.
The Hogwarts Express was going to have a "leg tickler" effect for the scene when the chocolate frogs get spilled. The effect was ultimately scrapped when the designers felt that it was too noticeable and too loud.
A Ministry of Magic ride was in development before they decided to build Hagrid's Magical Creatures Motorbike Adventure. However it’s rumored that it will come to Diagon Alley now that there will be more room (since the office buildings behind it are being torn down and moved to the Epic Universe lot) or be re-purposed into one of the foreign Ministries from Fantastic Beasts for the Epic Universe expansion.
An expansion codenamed "P195" started development, intending to be an expansion of Diagon Alley at Universal Studios Florida that would replace the Fear Factor Live stage. This was believed to be a virtual reality attraction that would simulate flying on a broomstick, and was adapted from a ride intended for the Wizarding World section at Epic Universe but cut from that location. The ride was fully cancelled in early 2022. Reasons for the cancellation have been rumored to include its similarity to another VR experience at the Harry Potter Store in New Yorknote that attraction was developed completely independently from Universal Creative, who reportedly only learned about it the day it was publicly announced, not wanting to crowd out the Epic Universe expansion, sudden difficulties with acquiring the permits to redevelop the land, and a creative push away from VR and screen-based attractions.
General Trivia:
After the midnight showing of Harry Potter and the Deathly Hallows: Part 2 at the Universal Cineplex 20 theater, Universal allowed all of the attendees into the Hogsmeade area until around 5:00 AM, to commemorate the occasion.
Of all things, J.K. Rowling was encouraged to let Universal build Harry Potter by Dr. Seuss' widow, as she had been very impressed with what Universal did with her late husband's work in the Seuss Landing area at Islands of Adventure. In turn, though he never met Rowling, it was the Wizarding World that convinced Satoru Iwata to give Universal the greenlight for Super Nintendo World in the final year of his life.
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