The Pokémon Toedscool and Toedscruel (divergent evolutions of Tentacool and Tentacruel) are called "OKAKINGU" and "OKAGYARADOSU" in the game's data respectively. This is interesting as these names seem to instead reference the names of Magikarp, called "Koiking" in Japan, and its evolution Gyarados respectively, meaning that the games were originally going to feature a pair of divergent evolutions for the Gyarados family instead of the Tentacruel family. However, there is no other data in the games but names for these scrapped Pokémon.
Contributed by PirateGoofy
Although the Paldea region is based on Iberia, its starters may take inspiration from the modern culture and fauna of New World places that Spain and Portugal colonized and influenced. Specifically:

•The Skeledirge line may represent Mexico. Its name, secondary ghost-typing, and skeletal imagery evokes Mexico's Día de Los Muertos (Day of the Dead), a celebration of the former lives of deceased loved ones where, among other things, celebrators may dress in flamboyantly colored costumes and paint skulls on their faces. Crocalor also has a head growth resembling a Sombrero. This and the line's theme of singing to attack may also be a reference to Mariachi folk music. In a fauna sense, Crocodiles are also endemic to Mexico.

•Quaquaval's influence may derive from Brazil's culture. This can be seen in the name which has elements of Carnival, a Catholic festive season popularly celebrated in Brazil with lavish parades. In addition, it being part fighting-type and being dance-themed may be based on the Brazilian martial art of Capoeira, a fighting style that heavily resembles dancing in many of its moves. Quaquaval is also based upon the South American Crested Duck.

•Meowscarada, while possibly taking inspiration from Iberia itself with its resemblance to the Iberian Lynx, could also take cues from the Southern United States, specifically the State of Louisiana. This is because New Orleans, in Louisiana, is known for its Mardi Gras (Fat Tuesday) celebrations as part of Carnival, which iconically feature performers in elaborate masks, hence Meowscarada's name evoking the word Mascarade. Although Louisiana was influenced by France, it was also conquered by Spain later, along with a lot of the Southern U.S. It may also be based on Louisiana's prominent diasporic religion surrounding Voodoo. Meowscarada's species may furthermore be based off of the Bobcat/Red Lynx, a relative of the Iberian Lynx.
Contributed by PirateGoofy
Tandemaus and Maushold may have dark origins as they may be based on the concept of a "Rat King", where several rats' tails are tied together or tangled by a person (although there have been reported cases of this happening without human interference). Explaining the German-sounding name of the Pokémon, the Rat King concept is named after the German term "Rattenkonig" which, in turn, is based on the villain of the same name from the short story "The Nutcracker and the Mouse King" who is sometimes depicted as being comprised of several mice or rats.

Also the Pokémon themselves may be aesthetically based on toy-like dioramic objects called "Sylvian Families" in Japan (or "Calico Critters" in English countries) which are essentially dressed-up mouse dolls in different whimsical small settings that make the mice look more like a human family. These Sylvian Families started in Japan in the 1980s, which is when many of the veteran developers at Game Freak would have grown up.
Contributed by PirateGoofy
The player can access a secret backup save file if they press X + B + UP (on the D-pad) simultaneously on the title screen. This save file works as intended even if Autosave is turned to OFF.
Contributed by PirateGoofy
In the mission Starfall Street, at the request of the enigmatic Cassiopeia, the player must face off against Team Star and their five leaders who command five sects of the group. Spoiler:Eventually, It's revealed that Cassiopeia is actually their leader manipulating the player to take down her peons. This is forehadowed through references in both Cassiopeia and the Team Star sects' names. Cassiopeia is the name of an M-shaped constellation in the night sky, and the names of the leaders' different sects are all the names of the five main stars of the constellation itself: Segin, Ruchbah, Navi, Schedar, and Caph. In addition, the geological positions of the Team Star leaders' bases on the map of Paldea reflects the appearance of the Cassiopeia constellation as well.
Contributed by PirateGoofy
Primeape's new Ghost-Type evolution, Annihilape, obtained by Primeape using the move Rage Fist 20 times, is a possible reference to Primeape's previous PokéDex entry about how it could suddenly die if it gets way too angry.
Contributed by PirateGoofy
True to their signature gimmicks, Zorua and Ditto like to disguise as different Pokémon in the overworld. One way to tell them apart from the rest of the species they are imitating is to closely examine the species' behavior and find one that's acting rather odd and out of character. A faster way is to use the games' new lock-on feature as the Pokémon's name on the lock-on's UI will display as "Zorua" or "Ditto" (or as "???" if you have not yet encountered either of the imitating Pokémon).
Contributed by PirateGoofy
The Pokémaniac Trainer Class has the symbol for Unova's PokéStar Studios (From Pokémon Black 2 & White 2) on the shirt they wear under their outfit.
Contributed by PirateGoofy
In the Academy's History Class, on the board behind Raifort, both professor Laventon and an old Hisuian Poke Ball from Pokémon Legends: Arceus can be seen.
Contributed by PirateGoofy
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In Alfornada there are Murals on and around the observatory that depict the original box and party menu sprites from the Generation 1 Pokémon games.
Contributed by PirateGoofy
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The headpiece worn by a Pokémon when they Terastalize into a Ghost-Type greatly resembles the Sprite used in the Gen 1 games for ghost Pokémon in the Pokémon Tower of Lavender Town that can be seen when the player goes there for the first time without the Silph Scope. It's also notable for being a sprite used by the Gen 1 glitch Pokémon MissingNo.
Contributed by PirateGoofy
Professor Sada and Professor Turo's names possibly come from the Spanish words for "past" and "future" respectively: "pasada" and "futuro". Spoiler:This is expanded upon by the fact that Sada plays an important role in Scarlet (which is past themed) and Turo plays an important part of Violet (which deals with the future).
Contributed by PirateGoofy
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The games' Paldea region is inspired by the real-life Iberian Peninsula in Europe where countries like Spain and Portugal are. In a lot of areas of Paldea, this can be seen:
•The Glaseado Mountains are based on the Pyrenees Mountains that separate Spain and France
•The large amount of caves in the region are possibly based on Spain's own large amount of caves, such as the Malaga Province's Caves of Nerja
•The real life Andalusia Region, known for its olive fields and sunflowers, is the inspiration for the Paldean cities of Cortondo and its similar olive fields, and Artazon and its sunflora connection
•Naranja/Uva Academy is architecturally based on La Sagrada Familia (The Holy Family) in Barcelona, an old landmark church that is still in an unfinished state to this day, among other inspirations.
•The regional variants on old Pokémon also reflect this; for instance, Paldea's black-furred Fighting-type variant of Taurus represents a Spanish Fighting Bull.
Contributed by PirateGoofy
Nacli, Naclstack, and Garganacl's English names all feature the shared letter sequence "NACL". This is referencing the scientific designation for the elemental compound of salt: NaCl (Sodium Chloride).
Contributed by PirateGoofy