Trivia: Spoilers! There are two credit scenes. In a mid-credit scene, a miniaturized Bowser tries to play his "Peaches" song again, only for a Toad guard to yell at him. In a post-credit scene, it is revealed that a Yoshi egg is in the sewers of New York. It begins to crack and the familiar voice of Yoshi is heard as the screen cuts to black.
Trivia: The movie came about partially thanks to the "Super Nintendo World" theme parks. As the Nintendo World parks were to be situated in Universal Studios theme parks, Mario creator Shigeru Miyamoto met many Universal executives, including Illumination CEO Chris Meledandri, to discuss the park's creation. Miyamoto felt Meledandri was a kindred spirit due to their similar creative processes and began talking with him about making a new Mario movie. Within a few years, the project was greenlit.
Trivia: When Mario and Luigi crash through the wall in the sewers, the hole they leave is the exact same shape as the original 8-bit sprite of Mario's head in the NES game "Super Mario Bros."
Trivia: In Mario's bedroom, not only is he playing the game "Kid Icarus" on the original Nintendo Entertainment System, but there's also a model of an Arwing from the Nintendo video-game "Starfox" hanging from the ceiling, and multiple posters with subtle references to different Nintendo video games on his walls.
Trivia: You can see the Crazy Cap store from "Super Mario Odyssey" in the background for a few seconds when Mario and Toad first arrive and are walking through the streets of the Mushroom Kingdom. It happens around the time Toad says the lines, "This guy's brother is going to die imminently, out of the way please! Just trying to clear a path, that's all I'm doing! He's gonna be fine!"
Trivia: When Mario and Luigi go to their plumbing job at the start of the film, when we first see the dog, the camera dramatically zooms out. If you look closely, most of the books on the bookshelves have titles like "Interior Design" or "Architecture", but there are a few random books mixed in that appear to have nonsense titles like "None" or "Nothing." I have to assume this is a background joke the animators added for people who would pause the movie.
Trivia: When the dog accidentally jumps out of the window and is saved by Mario, you briefly see the dog's owners sitting on the couch. The husband is reading a book called "Galaxy," which is a reference to the game "Super Mario Galaxy." Additionally, on the right side of frame, you can see a statue of a pikmin (a race of tiny, plant-like alien beings) from the Nintendo video game "Pikmin."
Trivia: During the scenes in New York City, you can briefly see a restaurant called "Chasse du Canard." This is French for "Duck Hunting," and is a reference to the Nintendo game "Duck Hunt," which often came paired on a cartridge with the original "Super Mario Bros." on the Nintendo Entertainment System.
Trivia: When Mario and Luigi get the Super Star and become invincible, at one point they grab Bowser by the tail and swing him around before throwing him through the air. This is a reference to the video game "Super Mario 64," in which Mario defeats Bowser by swinging him around by the tail and hurling him through the air into bombs.
Trivia: The film broke several box office records in its 5-day Easter holiday opening, including becoming the highest-grossing video-game movie of all time domestically, beating Sonic the Hedgehog 2's $190 million within five days. It also had the highest opening weekend worldwide for an animated feature. A few days later, it became the highest-grossing video-game movie of all time worldwide. It subsequently became the first ever video-game movie to gross $1 billion globally after four weeks of release.
Trivia: John Leguizamo, who starred in the original 1993 live-action film, criticized the film and attempted to get people to boycott it as he was upset at what he felt was a lack of Latin characters and actors in the movie. He also claimed that he was the "only one" who knew how to make the movie work. His comments have caused some confusion, as the film does contain several actors of Latin descent, and the titular brothers are Italian.
Trivia: Charles Martinet, who has voiced Mario in the games since the early 90's, has two cameos in the film. First is as an Italian man who talks to the Mario brothers at the pizza shop and whose voice is almost exactly like his Mario voice from the games. (He even lets out a classic "Woo-hoo!" just like Mario.) Second and much more subtly, he also voices Mario and Luigi's father, who appears at the beginning and ending of the film.
Trivia: When Mario and Luigi are racing to their first plumbing job at the start of the film, there's two really fun easter eggs. First, the entire scene is shown from a profile perspective to emulate the look of the classic side-scrolling Mario games. And second, the construction equipment and supplies they are running past are arranged to look almost exactly like the layout of World 1-1 from the original "Super Mario Bros." video-game. It's subtle and easy to miss, but once you see it, it's obvious.
Answer: "Princess Toadstool" was used in the original English-language manual, but she was Peach in the original Japanese, and that name continued in later versions, being combined with Toadstool. Bowser was originally called "Kuppa", but presumably the English-language version resonated more with people, plus removed any confusion of "Kuppa, King of the Koopas", so the English version stuck.