The lyrics to "Jump Up, Super Star!" perfectly describe everything that's featured in the game:
"Here we go": One of Mario's Catch Phrases, most notably whenever he collects a star or the different types of caps in Super Mario 64, reaffirming that Odyssey is returning to that gameplay style.
"Off the rails": About going from the linear gameplay of the Galaxy duo, 3D Land, and 3D World back to the open world style of 64 and Sunshine.
"Don't you know it's time to raise our sails": Referring to the sails on the Odyssey. As well as raising Nintendo's sales numbers.
"It's freedom like you never knew": On how the game is the most open Mario title to date.
"Say the word, I'll be there in a flash": You can now fast travel in this game.
"You could say my hat is off to you": A reference to Mario's new ability to throw his hat, the Capture mechanic (since the hat is literally going off towards whoever he throws it at), and the game's hat motif as a whole. It's also sung by Pauline, who is wearing her iconic hat (but not the rest of her items from Donkey Kong).
"We could zoom all the way to the Moon": Mario needs to look for Power Moons to help provide energy for the Odyssey. Also, most of the characters literally zoom to the Moon at the end of the game.
"From this great wide wacky world": All of the locales and denizens in Marios world are so strange and diverse, "wacky" is the best way to describe it all. It doubles as more than likely an unintended reference to Super Mario's Wacky Worlds, which coincidentially would've also featured Mario travelling the world.
"Jump with me, grab coins with me": Should be pretty obvious.
"I'll be your 1-Up girl"/"You're still our 1-Up boy": Ironically, this one doesn't qualify; this appears to be the first Mario platformer to not contain 1-ups in any capacity. Perhaps the line is meant as a Hand Wave for the lack of lives.
Alternatively, it could be a reference to when Mario and Pauline were a couple.
"I'm flipping the switch": Reference to the system the game was made for, the Nintendo Switch.
"Spin the wheel, take a chance": The game encourages you to take risks, like making leaps of faith into what looks like a pit, for a chance to find a secret.
"Every journey starts a new romance": The main plot is about Bowser trying to marry Peach, and Mario trying to stop him.
"A new world's calling out to you": The all-new and unique worlds Mario explores in this game.
"Take a turn, off the path": Again, reinforcing the game's focus on nonlinearity and exploration.
"Find a new addition to the cast": It introduces Cappy, as well as introduces new allies with every kingdom he stops in.
"You know that any captain needs a crew": Captain Toad is in the game, and Mario commands the Odyssey.
"Take it in stride, as you move, side to side, they're just different points of view.": The 2D sections where Mario goes into walls.
"Don't be afraid to get up and move": A call to the player to explore the kingdoms in whatever way they can.
Getting up and moving is also the very first thing Mario does once under the player's control at the start of the game.
Steam Gardens looks like a forest that has managed to grow over a nearby military factory. In addition, all of the citizens there are living watering can robots with sections made of wood.
The Ruined Kingdom is an After the End medieval-esque collection of destroyed castles. It doesn't have to contrast itself, it contrasts the entire Mario franchise in how gloomy and serious it is. The fact that Its sole inhabitant is a realistic dragon that looks like something from a Dark Souls game who is implied to be the one who destroyed it backs this up.
For the first time in the Mario series, Mario actually has definition in his hair and 'stache, rendered with strands in satisfying detail. Why they suddenly decided now to do this, however, makes perfect sense: this is the game where you're meant to regularly see Mario with his cap off, so he ought to still look impressive without it.
As explained in the Nightmare Fuel page, along with the loss of power in New Donk City caused by Mecha Wiggler, there are living military tanks and evil larvae. All set there by Bowser. The Fridge Brilliance is when you consider what the Metro Kingdom and Bowser's Kingdom are Fantasy Counterpart Cultures to. This could mean this sort of a stand in for Pearl Harbor.
It makes sense that if Pauline is meant to be Peach's romantic counterpart (even if only by implication) then she'd be in a position of power just like Princess Peach. Pauline is the Mayor of New Donk City, effectively making her the "ruler" of this new "kingdom".
Also, a bit of fridge brilliance comes in about Donkey Kong... The reason Mario was rescuing Pauline was the fact he was rescuing his home town's mayor, not some 'random' passerby.
Given the 2D section during the New Donk City Festival was touted as the town's origins by one of the citizens, it's quite possible Pauline ended up getting the city up and running again after the mayhem DK caused during either the original game or Donkey Kong '94, which likely caused her popularity to skyrocket among the citizens and nab her the job of Mayor (and considering her face is everywhere in the city, she's most likely the first and best mayor New Donk has ever had). Her ability to mediate situations and her business mindset were also hinted at in the Mario vs. Donkey Kong games, considering her opening up a theme park and being called to playtest the Minis. On a side note, we finally learned what her iconic red dress was for: that's her band's style!
If Donkey Kong '94 is how Pauline's first perils really went down, it makes since why she's New Donk's leader: getting dragged all over the land tends to help you remember what those locales are like.
The realistically proportioned humans in New Donk City were criticized at first for seeming out of place compared to Mario. But they match Pauline's build, and she would eventually be revealed to be returning as an important character related to the city. In the end, it makes a lot of sense to design the humans like that to match her more than Mario.
The Metro Kingdom's existence explains a lot about the early Mario titles; if Mario's first outing was in what would later become New Donk City, then his other urban adventures (fixing up the city sewer's pest problems, showing down a nasty foreman, and all those further mishaps with a certain stubborn ape) can be traced back to his time living in the endless cityscape of this kingdom. It also surprisingly lines up with the old DiC cartoon lore; since warp pipes are shown to exist around town, it's entirely possible that the brothers "found the secret warp zone while working on the drain" and ended up getting teleported to the Mushroom Kingdom by accident.
If this is all true, then the Big City and Big Ape City must have been colloquial nicknames for the same place ("Big City" before that "terrible day", and "Big Ape" after) before they finally settled on naming the town after its most well known event.note Or "New Donk City" is simply a Retconned version of the city from those two games (the retcon being that New Donk City had "always" been the name of the city).
The revelation that the various "kingdoms" aren't all ruled by kings, or even royalty for that matter, explains why the Mushroom Kingdom is ruled by a Princess. "Kingdom" is just what they call various countries in the Mario world.
In fact, in the French version of the game, they're named "countries".
Why does Mario no longer have a lives system? Because Pauline promised him that she'd be his one up girl, so he no longer runs out of lives.
And it's not a big deal anyway, since Coins have always been used in Mario games to get 1-Ups, only now it's effectively an upgrade, since instead of 100 (or 50) coins for a life, you only lose 10 of them.
The villains each wear a Nice Hat, which may look like an attempt to stay on-theme with the hat motif, but besides that, this is actually because Mario won't be able to Capture them this way, forcing him to fight them without Cappy's ability, on fairer terms.
The Broodals are rabbits who plan weddings. Considering the word "brood" in their name, and the common knowledge that rabbits are some of the most... reproductive... animals around, it makes sense that the experts on relationship progression would be bunnies!
Being rabbits also ties them to the game's overall hat motif, considering the classic magic trick of pulling a rabbit from inside a hat.
And the game's moon motif: in Asian culture, rabbits are strongly associated with the moon. It also helps that the Broodals are literal Moon Rabbits, hailing from the Dark Side of the Moon and assisting with weddings at the chapel on Honeylune Ridge.
Making most of the water in the Mexico-inspired Sand Kingdom poisonous may be a subtle "don't drink the water" joke.
Each Kingdom has their own unique coin, while the standard Mario series coins can be found in every kingdom. This is a nod to the real world, where nearly every country has their own currency, but United States dollars are considered the global currency.
The standard/regional coin divide was also unintentionally foreshadowed by Mario & Luigi: Superstar Saga. Not only did the Beanbean Kingdom have a currency separate from Mushroom Kingdom currency, the former currency was worth much more than the latter. In Odyssey, standard coins can buy you standard objects, while regional currency is much less common and is used to buy more unique items. Interestingly, picking up a regional coin youve already obtained nets you 2 regular coins, which proves that they are, in fact, worth twice as much as a regular coin.
Why are the Broodals searching for a ring that keeps the bride and groom together "even if the world is turned upside-down"? Assuming they weren't looking for it of their own accord before he met them, Bowser likely told them about the last time he married Peach (at least partially, depending on his and what he thinks is their opinions on the whole "marrying us brings forth anArtifact of Doom" matter), and either he or the Broodals themselves want to take some precautionary measures to ensure this second marriage doesn't unravel.
And indeed, in that wedding, the world IS turned upside-down: It's on the Moon. From the perspective of the attendees, the Earth would thus be in the sky.
The mooks seen in Bowser's Kingdom (with the exception of a few Goombas at the start) are all either wearing spiked helmets, inherently spiky (i.e. Spinies), or are tall enough that they can't actually be hurt unless they commit tactical suicide by giving you a platform to climb on. None are susceptible to a simple Goomba Stomp Bowser came prepared. It doesn't actually help him because your primary method of attack doesn't involve stomping in this game, but it still shows that he put some thought into how to fend off his nemesis.
In the endgame, when Mario captures Bowser, he's given six hit points before taking off in the escape gauntlet. How many times did you have to hit Bowser right beforehand to defeat him? Six (three rounds, two hits per round.)
The battle against the Cookatiel in Luncheon Kingdom is... weird. You use projected lava coming from the bird's mouth to climb up and bop it in the head. It's a Genius Bonus - in real life, vultures throw up vomit to scare away potential predators.
Doubling as Bilingual Bonus, the nobori in Bowser's Kingdom have the kanji "寿 (Kotobuki)" or "Long Life" written on them. Under it is Bowser's sigil, which if read in the Japanese style implies that the nobori can be read as "Long Live Kuppa" or "Long Live the King".
Many have remarked that the Mechawiggler isnt much like a Wiggler at all. However, consider its attack pattern while its generating portals. Its in an invincible state, furiously rushing forward. Sounds a lot like what a Wiggler does after being jumped on, doesnt it?
Aside from nostalgia, the Super Mario 64 outfit makes the most sense, particularly from a developmental standpoint, of being its own outfit. That game involved Mario frequently changing hats, and occasionally involved Mario losing his hat. While Sunshine and Galaxy also involve Mario without his hat, it's not to the same extent as 64. His model from 64 was made to frequently have no hat on and switch hats.
You might find it odd why Bowser is scared of Gold Mario...until you realize that in New Super Mario Bros. 2, Gold Mario can take Bowser out in one hit.
The fact that Peach pays no heed to the collapsed Ruined Dragon right next to her makes sense when you think about it. She's been kidnapped by turtle-dragons her whole life, so seeing a real one doesn't surprise her.
It seems rather odd that the Broodals go after you one at a time, especially when you face them on the Dark Side of the Moon, by which point you've beaten each of them twice already and ruined the wedding that they put so much hard work into preparing (and, if we take Rango's word for it, ruined their career as well). But think about how they attack Hariet throws bombs that leave long-lasting flames, Rango tosses a razor-sharp boomerang hat, Topper performs a breakdance with a ridiculously large tower of hats, and Spewart sprays poison all over the arena. And while Hariet and Spewart are unharmed by their own attacks, it's unclear if this immunity extends to the others. If two or more of the Broodals came at you at the same time, they'd probably end up hitting each other. And doing more harm to each other than to Mario doesn't help them one bit.
Why does Mario still have to worry about oxygen when wearing the spacesuits? If he's able to slip the helmets on and off that easily, then they must not be airtight. Water's still leaking into them.
The fountains being stopped up in Bubblaine is the perfect move on the villains' part. For one, it spitefully prevents any further production of Sparkle Water without their say. Second, it prevents the Bubblainians from reaching the new tyrant "ruler", Mollusque-Lanceur. But perhaps the real reason the fountains were shut off was for Mollusque-Lanceur's safety. After all, he's vulnerable to any pounding impact on his head, be it from Mario Ground Pounding or one of his own Gushens' jets. So if he was slurping Sparkle Water on top of the Glass Tower while the fountains were on, the four streams of pressurized water, which would arc right onto his head, would kill him instantly.
Luigi doesn't bat an eyelash at Mario wearing a wedding dress in itself, only commenting on what looks to him like an indication that Mario is getting married. Given Luigi has been depicted as a Wholesome Crossdresser on multipleoccasions, he wouldn't think much of it from his brother.
This is also an ability shared among all Bonneters: Put one on someone's head, and they'll be able to induce Capture. As long as the Cap Kingdom has at least one ally, that would make them an incredibly powerful military force should they engage in war with any other kingdom. (Looking on the globe, the geographically closest kingdom with a confirmed sentient population happens to be the Mushroom Kingdom. So if the Toads weaponise Bonneters, they can defeat an opposing army by knocking off their headgear and then taking over their bodies.)
That would likely have Bowser's forces scrambling for cover... for a while. After a certain point, Bowser would likely get fed up with the shenanigans. And he's already made a total mess of the Cap Kingdom before...
That said, chin strap technology might be all you need to stand against the rise of the Cap Kingdom.
The Broodals don't seem to care that the wedding they've been hired to plan has an unwilling bride. How many other kidnapping victims have they successfully married off?
Additionally, they go around stealing national treasures and messing up the livelihoods of the locals to meet their contracts. It seems that the lagomorphs really do lack scruples.
It is entirely possible that they normally just provide more conventional materials for most weddings. It is highly likely that Bowser, given his nature, commissioned the Broodals to acquire all the aforementioned items, because he wants his wedding to be the grandest ceremony of all time, as is only befitting his dream of being king of the entire Mushroom World. Given his constant raids on the Mushroom Kingdom and other lands, he probably has a sizable war chest to pay the Broodals for such an effort-intensive job. And he likely would've paid them extra had they taken out Mario in the process.
Should it be worrying that, in Bowser's Kingdom, you find Poochy by fishing him from a pool full of poison? Poison that's a One-Hit KO for Mario?
Poochy is completely invincible in every game hes in, so no.
Lost Kingdom shows us that at least parts of one ocean are poison. That's at least a bit concerning.
That being said, Lost Kingdom is full of life, which seems to have adapted itself to the poison. The toxic water is most likely naturally occurring.
Another thing about the Lost Kingdom... What would have happened if Mario and the heavily damaged Odyssey didn't hit that tiny island? Cappy could probably have survived by virtue of being able to float, but Mario doesn't have that ability.