Agares/Arglas and Zanza are both voiced by Takashi Taniguchi.
Author's Saving Throw: Shulk himself was explicitly stated by Takahashi as being this in regards to creating a likable protagonist. To be more specific, both of his previous protagonists had been very polarizing characters; Fei Fong Wong, the protagonist of Xenogears, had a habit of coming across as an Idiot Hero due to his Captain Obvious habits, and the fact he tended come across as angsty at times came across as grating to some, while Shion Uzuki, the protagonist of the Xenosaga trilogy, ended up becoming an extremeBase-Breaking Character in the last entry due to the direction her Character Development took (see the YMMV of Xenosaga for details), something that Takahashi didn't take well at all. Thus, he stated in interviews that one of his main concerns while writing Xenoblade was to make sure that the protagonist was likable during the entire story. And he seems to have succeeded, since Shulk is one of, if not the most beloved main character in all the Xeno franchises, with detractors being a clear minority.
Breakthrough Hit: While Monolith was originally known for developing several Cult Classics beforehand, it was Xenoblade's surprise success that would allow them to become recognized in the mainstream.
Celebrity Voice Actor: An interesting case. Jenna Coleman wasn't that well known when she originally voiced Melia in 2011. However, in the years after, Coleman gained worldwide recognition for playing Clara Oswald in Doctor Who, making her initial performance as Melia a case of Retroactive Recognition. Because of this, Coleman is now regarded as this when she returned to voice Melia in Future Connected, years after her tenure with Doctor Who.
Colbert Bump: Much like what Marth and Roy did for Fire Emblem, Shulk's inclusion in Super Smash Bros. sparked new interest with this game.
The Bionis' Shoulder, it was featured multiple times in early previews of the game, and the location is actually in the game data as a mostly fleshed out map. There were many theories on what purpose the map would have served, but was later confirmed to be meant for testing purposes and wasn't meant to be in the game. Averted as of the Definitive Edition, where the Bionis' Shoulder is part of the new epilogue, Xenoblade Chronicles: Future Connected.
The "Gadolt's Cannon" weapon for Sharla and the "Gadolt's Turret" material are both programmed into the game, but never used. Presumably, they would be obtainable as soon as you've defeated Gadolt within his Faced Mechon form.
Fanon: Some fans give Dunban and Fiora the surname "Uzuki," even though their actual surnames are never given (assuming they even have them, since most Homs have Only One Name). This is mostly a homage to Jin, Shion, and Citan Uzuki.
There was a theory that the Mechon that saved Juju and Otharon from the Telethia when Shulk and the party is going up against Dickson was actually Xord, due to sharing the same voice actor, though some were unsure that this was the case due to Xord exploding. The Monado Archives confirms that it was actually Xord.◊
As people completed Xenoblade Chronicles 2, there was an immediate suspect for where the dimensionally-lost Ontos core ended up. Definitive Edition confirmed this by changing Alvis' keyring necklace into what is clearly a dark red Aegis Core crystal.
Keep Circulating the Tapes: In the United States: The original Wii is now out of print from its highly limited run by one retailer. This gives it a high value to collectors. This is likely the reason why it got a port on the New Nintendo 3DS. The Wii version has also since been released on the Wii U Virtual Console, in Europe on August 5, 2015, North America on April 28, 2016, and Japan on August 5, 2016. Used copies can be found at nearly any Gamestop, albeit still at close to original retail price. Eventually, the game was remastered/remade for the Nintendo Switch as the Definitive Edition.
Limited Special Collector's Ultimate Edition: Xenoblade Chronicles: Definite Edition for the Nintendo Switch had a collector's edition upon release. The ones in Japan and Europe had an artbook and a soundtrack selection (with Europe soundtrack being on vinyl), while North America got the artbook.
Milestone Celebration: The release of the Definitive Edition occurred near the 10th anniversary of the original game's Japanese release.
Newbie Boom: Newcomers started rushing in in late 2014/early 2015 partially because of the protagonist Shulk's inclusion in the fourth installment of the ever-popular Super Smash Bros. series, partially because of Chuggaaconroy playing it, and partially because it got a much-needed re-release on 3DS and the Wii U Virtual Console. Eventually, its own popularity and that of its sequel resulted in an Updated Re-release for the Switch.
Posthumous Credit: Although Gorō Naya (Odama/Otharon), Takashi Taniguchi (Agares/Arglas and Zanza) and Sayuri Yamauchi (Laulan/Lorithia) died years after the game's release on the Wii, they are still credited for the Definitive Edition release since it contains the original dialogue.
Role Reprise: While the main game's dialogue is the same as the original release, all characters in Future Connected had their original voice actors reprise their roles, including Jenna Coleman as Melia in the English dub.
Sleeper Hit: The game didn't receive a lot of advertising or recognition by Nintendo upon release in Europe, but positive reviews and word-of-mouth (courtesy of Operation Rainfall's efforts) made the game sell rather well, to the point where they had shortages of available copies because of the surprisingly good sales. The fact that it's the Spiritual Successor to cult classicsXenogears and Xenosaga also helped.
There is are also a few explorable maps that were Dummied Out of the game (though still accessible by hacking). The most prominent of these are a large, elaborate map set on Bionis' left shoulder, and a map for the Colony 9 created after Zanza's defeat, implying that a post-game was to be included at some point in the game's development. Bionis' left shoulder returns in the new epilogue of Definitive Edition, finally averting this.
Dickson, Mumkhar, and Alvis all have unused dialogue, including for attacking high level enemies (Mumkhar never rejoins the party after the Battle of Sword Valley, Dickson only joins in battle against Metal Face after Central Pit, and Alvis only fights when Shulk encounters the Telethia for the first time and gets Monado Purge), burst affinity quotes, retreat quotes, KO dialogue (Alvis can't die in his only fight in the game), and Shulk, Fiora and Reyn would have Tephra Cave battle lines exclusive to the Ether Cylinder quest.
Shulk originally had 6 swords before getting the Monado, including the Debug Sword which was, aesthetically, the True Monado, despite being treated like a regular sword, which was done to test out specific areas. Sharla would've also received Gadolt's Cannon after Mechonis Core.
There was originally going to be an enemy called 'boss', who had no animation when he was scrapped.
Interviews allude to a plot point where, in response to Sharla's death, Reyn would discover a way to time travel and risk the lives of countless people to bring her back, putting him at odds with Shulk, and leading to Shulk using the power of the Bionis against Reyn who would wield the power of the Mechonis in a fight to the death. The development team, however, did not feel comfortable having Shulk's closest friend betray him. The final game does involve a traitor in the midst—Dickson—though he is not as involved in the party.