References to previous Final Fantasy games and other media

[Wolf Kanno]

The Invincible is named after the airship from FFIII but even more amusing, it's design shares many similarities with Amano's concept artwork for the Enterprise

586px-FFIV_-_Amano_Enterprise.jpg vs. Ffix_invincible.jpg

A further connection to FFIV is that fact the Invincible fulfills the same role as the Lunar Whale in FFIX by being a ship capable of traveling between the two worlds.

The Iifa Trees Theme is actually based off of FFIV's Another Moon Theme

Also, the Crystal World Theme is a remix of Prelude, the reason being, that Prelude is often the theme used when characters encounter the crystals in the early FFs like FFIV.

FFIX has a hidden mini-game much like the matching game in FFII unlocked by screwing with the Snow Sled and other NES games. At the end of the game when Prelude is playing and The End appears, if you put in a certain button combination, you can play Blackjack.

The Treasure Hunter Rank is a reference to FFTactics, where you could also raise your Treasure Hunter Rank by doing Propositions, and collecting FF artifacts.

Gilgamesh, known as the Four Armed Man in the game also makes a sly reference to Locke Cole of VI by being associated with the Treasure Hunter Quest and calling himself a great Treasure Hunter but he's also a blatant thief in the game. :ffvipatpat:

[Tigmafuzz]

I can't believe you all missed the biggest one in the whole game.
It's called "Final Fantasy." That's like the ultimate reference.

Just kidding, calm down. But you did miss some.
FF1: The key item Rat Tail is a reference to the Cave of Ordeals in FF1 when Bahamut asks you to find it in order to prove your courage.
In the description of most of the key items needed to make the Supersoft, there is a reference to Matoya from FF1.

FF3: Not really a reference, but moogles originated in FF3.

FF4: This is probably an FF8 reference, but the attack Darkside could also be a reference to Dark Knight Cecil's special command, called "Dark Wave" in the Japanese version. Only difference is that Dark Wave hits all enemies, and Darkside only hits one.
The Rat Tail made another appearance here, as an item you could trade for Adamant.
The Antlion in FF4 was supposedly tame, yet attacked Prince Edward anyway. In 9, he attacks Prince Puck.

FF5: There's a card called Boco in FF9, referencing Bartz's chocobo.
The Airship card has the sprite of the airship from FF5. Or 4. They both look the same.

FF7: Kupo Nuts. Come on, guys. The Mog House mini-game?
The moogles' "kupo" sound effect is the EXACT same one. Not even joking.
After Alexandria is destroyed, one of the Pluto Knights is talking to a flower girl near the ruined steeple. If you talk to the flower girl, she'll say "He's nice, but isn't much for personality." Remind you of another flower girl and lacking-in-personality soldier?

FF8: Beatrix's Save the Queen was Quistis's ultimate weapon. It was also used in Tactics.
Quina's Eat command. Though the effect is different, it's the same command as Devour in FF8.
The spell naming system (Fire, Fira, Firaga) was the same as in 8. Actually, it was the same in almost all the Japanese FF games.

FFT: The Stellazio coins in 9 are named after the Zodiac. Tactics was the first RPG (I think) to include these. There's even a 13th Stellazio, although not Serpentarius.
The Auto-Potion support ability.
A lot of Steiner's Sword Art abilities (Mental Break, Armor Break, etc.)

There are some references to the GameBoy Final Fantasy games as well, including bosses from the Final Fantasy Legend games and something specialFind it yourself. from Final Fantasy Adventure.

SaGa Frontier 2: Did Gustave have something to do with the construction of Lindblum and Alexandria? Like his homecity in SaGa Frontier 2, Hahn Nova, Lindblum has three sectors: Industrial, Business, and Theatre. Think "Blacksmith", "Shopping", and "Entertainment". Similarly, take a look at Alexandria from the world map. The castle sits in the center of the lake, with three segments of the town divided by rivers. Hahn Nova has a very similar setup: The castle in the center of town and roads seperating three sectors of town. Probably a coincidence, but interesting nonetheless.

Parasite Eve:In the Lindblum Synth Shop, the owner is named Torres, and the man at the counter is named Wayne. These were the two people in the NYPD weapons room on PE. In addition, when you first enter said shop, the two of them have a skirmish which is practically the same as the "Safety vs. Power" lecture you overhear when you first enter the NYPD weapons room.

[Bolivar]

Didn't know about the other Square games, that's really awesome!

Also I think you should tell us what the final fantasy adventure one is, nobody wants to play that ish.

[Gamblet]

FFT: The Stellazio coins in 9 are named after the Zodiac. Tactics was the first RPG (I think) to include these.

Aww, I wanted to say that...

[Tigmafuzz]

tell us what the final fantasy adventure one is, nobody wants to play that ish

The "Tree of Mana/Tree of Life" plot worked so well in FFA, that they decided to continue with the SaGa series. They were going to go with an underground crystal cave, but someone mentioned either Romancing SaGa or SaGa Frontier in a passing conversation, and they ended up with the Iifa Tree. So if it weren't for Seiken Densetsu being remade as Final Fantasy Adventure/Mystic Quest, we would have had a crystal cavern or something instead of a mist-filled Yggdrasil. Not a reference, but pretty awesome.

[Bolivar]

^ that is pretty awesome.

[Depression Moon]

Just beat FFV and Bartz says you're not alone to Krile. Maybe the song is a reference to that?

[Silent Warrior]

Just spotted this paralell with FFVII:
Jumping from an airship

You know the scene where you paradrop into Midgar after beating Diamond Weapon, right? Reminds you any of warping to Terra?

Also, Biggs and Wedge from Star Wars tends to be a staple in the series, but I can't actually remember seeing them in FFIX...

[Quindiana Jones]

Oh god, I'm too scared to even begin talking about the music from FF9 and it's parallels to every other FF. xD

[Gamblet]

The cloak that Zidane is wearing in the ending of the game looks a lot like the executioners outfit that Gafgarion wears in Final Fantasy Tactics. ( at Golgorand)

EDIT: And the way they remove the cloak is the same also.

[Jiro]

Also, Biggs and Wedge from Star Wars tends to be a staple in the series, but I can't actually remember seeing them in FFIX...

A quick google search yielded nothing. Was the "tribute to old school FF" the first in a long time to forget Biggs and Wedge?!

[Silent Warrior]

... Uh... I've just gone on another playthrough of FF9, and up to smacking Garland I have yet to find any Biggs or Wedge! Horror! Still, I haven't engaged every NPC I've met in conversation... I'm sure they'd have been part of the Knights of Pluto - their given place, what with FF8, eh?

Anyway, I think there's one more thing we've forgotten to point out:
The planet's circle of souls sounds a lot like Lifestream from FF7/Gaia theory in Spirits Within.

And one mistake in the original post: The fountain with the medal message is in LINDBLUM, not Treno. Edit, yo! Chop-chop!

[charliepanayi]

There is no Biggs and Wedge in FFIX from what I can remember, and the FFWiki I've checked makes no mention of them.

[Tigmafuzz]

You can find Vicks hiding in Maduin Sari. It's offscreen to the right.
You can find Wedge in the forest NE island at top.

[Depression Moon]

screenshot?