1001 Video Games
The PS1 version of Xenogears appears in the book 1001 Video Games You Must Play Before You Die by General Editor Tony Mott.
A companion artbook called Xenogears: Perfect Works exists. In addition to containing tons of original art from the game, it also contains details on events, character names, places and references to the backstory including all the other Xenosaga games (published years after Xenogears)
There was some controversy surrounding the US release of Xenogears regarding the religious context of the title. Apparently the game was originally going to be heavily edited during the translation process. The reason? the game makes use of lots of catholic references (the Babel tower even appears as a location in the game) and makes some...controversial allegories on the game (ie. -SPOILER- the major religion on the planet turns out to be an entire fraud and a front to exploit people, etc). Fortunately save some item/monsters renaming the entire translation ended up being faithfull to the original.
German Language Usage
The creators of Xenogears made much use of the German language, in particular when naming the gears. A large amount of gears' names are actually German words. For example, "Weltall" means "universe", and "Stier" is "bull". Two gears are named Achtzehn and Seibzehn: the first word means "18", and the second would have meant "17", if it were not incorrectly spelled: the German word for 17 is "Siebzehn". Another gear is named "Vierge"; this is not German, but French, and means... "virgin". Hmm. If you say so... ;D
Kislev, the name of one of the two rival empires of the game's universe, is actually just a month of the traditional Hebrew calendar!
There's a ton of sci-fi references in this game, both to the obvious japanese "giant robot" series, as well as some western sci-fi. For instance, the elements final form of attacking you is by joining their gears in an exact replica of all the Super Sentai (Power Rangers, etc.) sequences; When the Yggdrasil joins the Norturne city to form the super-gear you see it's called the "Super Dimensional Gear Yggdrasil" this is a reference to the old Robotech show were the big city-ship SDF-1 transformed itself in a giant robot (on the original japanese version (Macross) the ship was called Super Dimensional Fortress Macross).
References to western sci-fi include the name of the ship in the opening, the USS Eldridge (remember the Philadelphia Experiment?) and the Soylent System, which is, of course, made of peopleeeeeee!!
Heavy references to the Bible are found in abundance in "Xenogears". The old legend about the first humans who ate a forbidden fruit and thus "became like gods", which is the core of the game's story, is taken from the beginning of the Old Testament. The Babel Tower also appears in the first book of Moses. There are some subtler references. For example, the three wise men Gaspar, Balthasar, and Melchior are the exact names of the three mages who visited Jesus in Bethlehem.
Lucca from Chrono Trigger makes an appearance in Xenogears. She can be found right in the beginning of the game, in Lahan's Information House, teaching you about save points.
There is a special edition of the game available in Japan as part of Squaresoft's Millenium Collection. The game is the same but can be found on two different packages with brand new cd art, one featuring Fei and the other Elly. Also the Fei package comes with a Fei and Bart plastic figure and the Elly package comes with Elly and Chu-chu.