The series in general, or to multiple games at the same time
In the "Revenge" trailer, Clive is accompanied by Jill and Cid; the Dominants of Ifrit, Shiva, and Ramuh respectively. This particular trio are often grouped together as the first summons available in earlier Final Fantasy titles. Clive and Jill's close relationship in particular references Ifrit & Shiva's close association throughout the franchise as well.
Two recurring weapons, the Braveheart (in its Dissidia design) and the Blood Sword (in its Final Fantasy II design) appear as DLC content.
There are numerous throwbacks to traditional Final Fantasy jobs.
The Dominant boss battles all use a fighting style reminiscent of a job. Benedikta is a Berserker, Kupka is a Martial Artist and Barnabas is a Dark Knight.
An early game boss uses many of the animations and attacks of the Rogue/Ninja, though his take on Futon is very different from the generic speed increase the incantation normally provides. Similarly, most spell casters, axe wielders, and lancers directly lift the casting, idle and attack animations from the Thaumaturge/Black Mage, Maurauder/Warrior, and Lancer/Dragoon respectively.
Fields in Rosaria contain scarecrows dressed as Black Mages.
The heroes' second lair is in the wreckage of a crashed Fallen airship named the Invincible, a common name for particularly advanced and powerful airships in the franchise.
Similarly, the naval ship Mid ends up building is called the Enterprise.
A mid-game A-Rank Hunt in Rosaria is a trio of Crusaders named "The Mageth Brothers", evocative of Magus Sisters, a recurring boss/summon in the series. They even have a similar naming scheme, being named Sandwydd, Cindwydd and Mindwydd in relation to Sandy, Cindy and Mindy.
The Masamune can be found in Waloed in a chest next to the Chronolith for Shiva.
One of the numerous names Byron Rosfield gives his trusty axe is Ogrekiller, which is a recurring weapon found in the older games.
The spoony bard's real name ends up being Lukahn Larkstongue, after the sage.
Charon can be seen as a reference to Matoya - both are grumpy old women with a fake eye who help the heroes.
Ultima's early boss themes use Final Fantasy's main/overworld theme as the vocal melody.
At one point, Clive uses the alias "Lord Underhill." Lord Underhill was initially mentioned by an NPC in Final Fantasy I, which was originally thought to be a reference to The Lord of the Rings.
The item description for the garlic Clive needs for a particular quest states that Sanbreque honors those who provide the seasoning with the title of "Garlic Knight", a play on the default Onion Knight class.
One of the bosses during the prologue is a dragoon named the Knight of the Blinding Dawn. Before the Knight jumps down to the field, he takes the same stance as Kain's iconic pose from Final Fantasy IV.
There's a "spoony bard" in the hideaway.
At one point, Jill pretends to be someone named Jayne, captain of the Red Wings.
Clive's Battle in the Center of the Mind against the "Infernal Shadow" - who appears as a Superpowered Evil Side is very reminiscent of Cecil's battle against the Dark Knight, both representing the heroes' regrets and fears about themselves, and both resulting in them coming out of the battle stronger for it.
The main story quest "Into the Darkness" shares its name with the dungeon theme from Final Fantasy IV.
The combat system was heavily inspired by FFV's job system, as confirmed by the developers. V would have you learn multiple jobs in order to master their skills and combine them with other jobs. Similarily, XVI gives you 7 Eikons of which you can only equip 3 at a time, with each one having 2 ability slots. Initially, you can only equip abilities associated to their Eikon, but by mastering them you can equip those abilities onto any Eikon. Coupled with the option to refund skill points, this gives the player a lot of customization on Clive's skills, encouraging players to mix and match in order to accommodate their playstyle.
The character Mid originally appeared in V. Furthermore, she makes a reference to a historical "Bartz the Builder."
The village of Moore can be seen as a reference to the Forest of Moore, which also contained a village of the same name. Much like the original, the dungeon that follows ends with the Big Bad killing a party member.
Two bosses from Final Fantasy V make their appearance: Liquid Flame and Necrophobe, later on.
Clive's destruction of the Mothercrystal at Drake's Breath is very reminiscent of the destruction of the crystals in FFV, with white particles of light extending in an arc that cover the foreground of the screen like the fragments of the four crystals that give Bartz's party their jobs.
The barrier Barnabas creates around Stonhyrr recalls the one around Exdeath's Castle, needing to be destroyed before access is granted. The city also has a prominent bridge leading to the Mothercrystal, but no one is fought on it this time.
After fighting their way through Stonhyrr, Clive and Joshua get swept away by Ultima to the Interdimensional Rift.
Gaining an Eikon's power and their associated moveset that enhances Clive's skills throughout the game is reminiscent of Espers granting its user(s) their spells and status boosts.
The Veil brothel and its occupants are one to the Veil Dancer enemy.
In one sidequest, a group of bandits name drop their leader, Locke, that Clive had previously killed.
Late-game backstory reveals there was once a "War of the Magi" that occurred in Valisthea's distant past.
Clive's time as a slave soldier killing untold numbers of enemy combatants is similar to Terra's plight when VI opens.
Ultima casting Primogenesis leads to the world becoming darker, more dangerous and occurs when the Empire falls and politics takes a backseat in the narrative. This is similar to VI's "World of Ruin".
The game ends with the death of a god and the destruction of magic. Clive's fate is also similar to Terra's; both destroyed magic knowing it could be their end, but while it's clear Terra survives it's less so with Clive.
Clive's false memories of the events of Phoenix Gate mirror and invert Cloud's false memories of the events of Nibelheim. Like Cloud replacing Zack with himself due to the trauma of what he had been through, Clive replaces himself in his own memory with an unknown figure who never actually existed. Clive, like Cloud, eventually comes to terms with his memories, and the player is shown another flashback depicting the true events of what happened in the past.
There is a sword named the Gaia Blade that bears a rather uncanny resemblance to the Iron Blade from Final Fantasy VII Remake. Gaia is also the name of the planet from Final Fantasy VII. Furthermore, its description states that it was made by people that worship 'the land itself', not unlike how many in Final Fantasy VII's world do.
The Mothercrystals draining the land of aether and causing the Blight is similar to the Mako Reactors draining The Lifestream and causing the planet to die. And like AVALANCHE, Cid aims to destroy the Mothercrystals to save the world from being drained dry.
The final stage of Ifrit Risen's fight with Bahamut involves him plowing through Zettaflare and striking down Bahamut, just like Cloud's battle with Bahamut SIN in Final Fantasy VII: Advent Children.
Ultima summons a storm that blankets the land in darkness with a casual raise of the hand, just like Sephiroth in Advent Children.
After hitting Ultima Prime with Tri-Disaster, one of his wings is cut off and leaves him with only the one black wing. To add to Sephiroth's imagery, he drops a gigantic flaming ball of fire on to the heroes whilst having the one wing.
The Echoes of the Fallen DLC comes with Cloud's Buster Sword.
Clive obtaining the Eikon powers after defeating Dominants can be likened to drawing Guardian Forces from enemies.
The scene with Clive holding one of the Phoenix's feather after Joshua's second death is a direct reference to the scene of Squall watching one of Rinoa's feathers fall.
The Angra Mainyu boss in "Echoes of the Fallen" has an attack called "Eyes on Me", after this game's love theme.
Dion's suspicion of his father's intent on waging war on Valisthea coming from an outer source manipulating him (in this case Ultima) echoes Garnet's story with her mother Queen Brahne being manipulated by Kuja. Much like Brahne, emperor Lesage also suffers a tragic end.
A late game event causes the world to be filled with aetherfloods, similar to the Mist covering the continents in IX. Furthermore, both are considered dangerous due to the monsters that lurk within.
One post the player can read is a work order for weapons from a knight named Adalbert Steiner.
Numerous scarecrows can be found around settlements that bear a strong resemblance to Vivi/the Black Mages.
A major city is devastated by Bahamut, and it requires another summon intervening to stop him. Unlike previously however where Alexander was the protector of Alexandria, this time Bahamut was meant to be the defender of Twinside but it has gone berserk and needs to be stopped by Phoenix and later Ifrit before it destroys the city it's meant to protect.
The first phase of the battle against Titan Lost - where the boss attacks with numerous, giant, vine-like tendrils while the protagonist runs up and along the tendrils, ducking and weaving through - bears a great resemblance to Zidane's final run through the Iifa Tree during the game's ending.
In the prologue, Clive whistles exactly like Tidus and Yuna do.
The finale also brings elements from X's ending where the protagonist sacrifices himself to save the world, with their loved one mourning their loss. Similarily, X ends with Tidus swimming back up from the ocean; while Clive ends up washed ashore next to the ocean, with their fates remaining ambiguous (for Clive at least, as Tidus comes back for X-2).
Many of the Beastmen enemies, especially the Goblin and Orcs, reference types of Beastmen enemies in Final Fantasy XI, such as Goblin Muggers, Orcish Mesmerizers, etc.
The term "notorious monster" originated in XI, but XIV uses it as well for certain (non-hunt board related) field monsters.
Cid being the Dominant of Ramuh seems to be a big Final Fantasy Tactics joke, making him a very literal "Thunder God Cid".
Much like in Final Fantasy XII, the game features two Cids who are unrelated to each other, as well as a person named Margrace who is connected to one of them: the first Cid is Cidolfus Telamon, while the second one is Clive who takes on the name "Cid the Outlaw", and Margrace is his younger brother Joshua.
A notice posted in Clive's office about Fallen relics in the Velkroy Desert comes from Tomaj, of the Second Order of Archaeologians, named after Tomaj, the owner of the Sandsea Tavern in Rabanastre.
Jote has the same name as the leader of the Viera in XII.
The Undying, sans Cyril and Goditha, seem to take names from various characters in XII as their code name. Tomaj, Dalan, and Kytes are all names mentioned. Clive even notes that they are not Rosarian names.
One of the notorious monster hunts is a morbol called Carrot.
For that matter, the hunt board system itself started with XII, and the icon for it references the original Rogue Tomato hunt mark.
Bearers are similar to l'Cie. In both games, they are persecuted people with the ability to wield magic. When a Bearer overuses their magic, they eventually turn to stone and die, and when a l'Cie fulfills their Focus, they turn into crystal.
"Eikon" is Valisthea's term for summons, the same term the Garlean Empire uses to refer to what Eorzeans call "Primals".
The Limit Break gauge looks exactly as it did in XIV: divided into three sections, with a blue bar turning gold as it fills each one.
At max level, Clive can stack up four limit break bars like the Warrior of Light battle in the "Seat of Sacrifice."
The concept of people transforming into summons seems to be lifted from XIV, wherein some individuals transformed into Primals by summoning them into their own bodies rather than summoning a separate entity altogether. The most notable example is Ysayle Dangoulain, who regularly transformed into Shiva; at one point even battling another Primal as Shiva, likely inspiring XVI's many Eikon duels.
Garuda's design borrows heavily from her XIV iteration, even being fought in a dark stormy forest again. Also, one of Clive's skills as he's channeling her powers is Wicked Wheel, XIV Garuda's Signature Move.
In addition, during a fight with Benedikta she tells Clive to "Now fall", referencing the lyrics of Garuda's theme in XIV.
Similarly to the above, Ifrit is a mix of the more commonly bulky, Minotaur-esque design of the Ifrit of older games, and the reptilian form he takes in XIV.
The deadlands are identical to the Burn; a gray wasteland drained of aether and unable to sustain any life.
One of the attacks Bahamut employs during his boss fight is called Mortal Coil, the English translation of his signature move Akh Morn in XIV - previously only ever known by its dragon language name. He also uses an attack identical to Megaflare Dive from XIV, as well as that game's iconic version of Teraflare.
A small, bright red star named Metia can always be seen next to the moon, most clearly in several nighttime conversations between Clive and Jill. The resemblance to XIV's red moon Dalamud prior to its fall is uncanny.
The imperial dragoon fought in the prologue has the same English voice actor as Estinien, XIV's most prominent Dragoon.
Barnabas bears a strong physical resemblance to the Warrior of Light's cinematic template: in full Odin getup, he's a dead ringer for the Shadowbringers incarnation of the Warrior, whose altered title Barnabas's own borrows from. As The Dragon, The Heavy, a Manipulative Bastard, and ultimately an Omnicidal Maniac, his portrayal could not be further from XIV'sIdeal Hero, for all the pair hail from commonroots.
A device called an Orchestrion can be used to re-listen to the game's OST by buying Orchestrion Rolls - exactly like in XIV.
A late-game A-Rank Hunt in Dhalmekia is rainbow chocobo called the Dread Comet, a nod to the Red Comet. It's a powerful chocobo that can cast meteors and give Clive a hard time.
The boss fight against Titan Lost is similar to the Savage Mode version of the Heritor Titan fight, the music playing has a similar beat to "Under the Weight".
Also for Titan: when the player battles against Hugo, he says "my hatred for you is unending, unyielding!" to Clive. Titan says the same thing in XIV before having Titan's Heart emerge during the fights against him. Hugo follows the quote up with a barrage of attacks directly taken from XIV's Titan fight, such as Landslide, Tumult, Geocrush, Upheaval and Weight of the Land.
Torgal gains his own Eikon form as Fenrir. According to Tomes, being a wolf from the northern realms, he descends from wolves that have been able to manifest eikonic powers due to the influence of Shiva Dominants like Jill, he even develops this form to protect Jill, much like how Fenrir is related to Lady Iceheart in XIV.
Blackthorne is a grumpy and aloof blacksmith that left his home to dedicate himself only to improve his craft and will refuse to hear out the main character until they bring him alcohol, just like Gerolt Blackthorn.
The most prominent enemy types of Sanbrequois soldiers are Dragoons, Astrologers, and occasionally even a mini-boss called a Cannoneer - three of the four jobs associated with Ishgard, their inspiration (Dragoons, Astrologians, and Machinists respectively; only Dark Knight is unrepresented).
Similarly, the land where Dragoons hail from is a theocracy with a long and convoluted relationship with dragons, making it an obvious parallel to Ishgard.
Nektar the moogle uses the same moogle design as in XIV, except he is more detailed.
Mid's workshop in Kanver is called the Ironworks, referencing Garlond Ironworks of XIV.
The Sanbrequois government has a council named the "Rowena Syndicate". Rowena is an Intrepid Merchant in XIV responsible for the sale of endgame equipment.
Clive gains the power of other Eikons by absorbing their aether. Being exposed to the aether of Primals is narratively how Summoners in XIV gain the power to summon primal egis.
And speaking of Egis, both Benedikta and Barnabas are able to create their own Egis, Benedikta is able to create Chirada and Suparna at will (both of which appeared as her attendants during her boss fight in XIV), while Barnabas is able to summon hundreds of copies of Sleipnir, though he is a humanoid and not the usual six-legged mount.
While not present in the base game itself, Leviathan is shown in the murals along with the other Eikons and his appearance is almost identical to how he is portrayed in XIV.
He is also referenced in the name of the quest "Through the Maelstrom", named after the patch where Leviathan was introduced in XIV and one of his boss themes.
Leviathan was eventually added as a boss and an Eikonic power in The Rising Tide DLC.
The Akashic are based on the Blasphemies from Endwalker, both of which are soulless mutants with little will beyond rampaging and killing, with the Big Bad seeking to wipe out all life in a process that involves transforming as many people as possible. The name Akashic itself homages dynamis, the energy at the center of the Blasphemies, in that the region of Thavnair refers to it as akasa, an alternate spelling of the Indian term akasha.
Lady Charon uses the word "popoto" rather than "potato", showing that the Twins use the same word for the food as in Eorzea.
Clive's penultimate blow in the final battle against Ultimalius is to empower his sword with flames and hurl it at Ultimalius, piercing him through and leaving a gaping hole in his chest, mirroring how the Warrior of Light defeated Hades by hurling an axe of light through the Ascian. Both Ultimalius and Hades even survive long enough afterwards to have a brief conversation with their respective foes.
The Sagespire background music and the Omega boss theme "Eikonoklasm" in the Echoes of the Fallen DLC are arrangements the Azys Lla theme "Order Yet Undeciphered" and Omega boss theme "eScape".
Failing the final phase of the fight against Omega results in it using an instant kill called Omega Protocol. The Omega Protocol is the name of the Ultimate level fight against Omega in XIV. It also uses various other abilities associated with Omega in that game, most notably Pantokrator.
A re-imagined version of the level 50 paladin relic weapon Curtana comes as a bonus item with The Rising Tide DLC, along with orchestrion rolls of the A Realm Reborn boss theme “Torn from the Heavens” and Leviathan theme “Through the Maelstrom”.
In XIV, the party has to erect a barrier to prevent Leviathan's Tsunami from wiping them out. The Rising Tide reverses this, as Leviathan is the one who erects a barrier and Clive has to destroy it to stop him from casting Tsunami. Notably, the music for this part of the fight changes to a remix of “Through the Maelstrom” from XIV.
It's revealed in The Rising Tide that a past Dominant of Shiva was named Ysay. In XIV, a woman named Ysayle gained a similar ability to Dominants and could transform into Shiva.
A game where you take control of a prince whose father is murdered and more than a decade later the world is plagued by the Starscourge/Primogenesis and the only way to save it is for the hero to sacrifice himself? Where have we seen that before?
The Blight appears to take several cues from the Starscourge, being a mysterious plague that is connected to the Crystal(s).
Jill's outfit and weapon as an adult is evocative of Stella Nox Fleuret, Lunafreya's precursor from when XV was Versus XIII.
The Phoenix Shift looks similar and functions very similarly to Noctis' and Ardyn's Warp Strike ability.
The Timekeeper's third phase in The Rising Tide unleashes and uses many styles of weapons, essentially having it's own Armiger.
Others
Clive's pet wolf (which showed up first in the "Awakening" trailer) is named Torgal, after one of the characters from The Last Remnant.
The term Bearer has been used in the series before. But while in XVI Bearers are humans with the ability to use magic without crystals, in Final Fantasy Crystal Chronicles: The Crystal Bearers, Crystal Bearers were able to use magic because of the crystals embedded in their bodies.
One of the Undertaker and its variants' special moves is called "Spirits Within".
Thanatos, an Notorious Mark Undertaker variant, has an attack named "Spirits Without."
This is also doubles reference to Final Fantasy XIV: One of the abilities that Gladiators/Paladins get is called Spirits Within - and the version of the ability used by NPC enemies is called Spirits Without.
