References to Final Fantasy X and Final Fantasy X-2

 1. When you're looking for information on Titan you find Trachtoum, a complete liar who even mispronounces Titan's name as Tidus.

References to Final Fantasy IX

 1. The Moogle Mail system is similar to that of the Mognet from Final Fantasy IX.

References to Final Fantasy VIII

1. The card game, Triple Triad, is exactly the same Triple Triad from Final Fantasy VIII. In FF VIII you used the game to recieve cards that you could either keep or turn into items that could also be turned into Magic. In here it's just for fun.

The theme that plays in Triple Triad matches in FF XIV is the same one that plays when you play Triple Triad in FF VIII: Shuffle or Boogie

Shuffle or Boogie (FF VIII)

References to the Compilation of Final Fantasy VII

 1. Biggs, Wedge and Jessie, three engineers in Cid's company, Garlond Ironworks, are all named after the AVALANCHE members of the same name. While Biggs and Wedge are characters in many Final Fantasy games (named after characters from Star Wars) the inclusion of Jessie makes it likely they based them after their Final Fantasy VII incarnations.

Biggs (Left) and Wedge (Right)

Jessie

References to Final Fantasy VI

 1. The server called Figaro in 1.0 referenced the kingdom from Final Fantasy VI with the same name.