Lead writer Greg Farshtey has said that the Vahki are his least favorite characters in the series. He is also not fond of writing characters who speak Treespeak. Vakama's out-of-character FaceHeel Turn, which he had no say in, reportedly made him mad since he would have chosen Matau instead.
According to Farshtey, Bob Thompson (the original head of the story team) disliked the Exo-Toa set and asked the writers to diminish its role in the story.
Given that the alpha v0.006 build is very unfinished, there are plenty of game files that are unused in the game itself. For a more traditional example of this trope, three unused sound files for Kopaka's level (dcsnowwind.wav, Iceman.wav, and Melting.wav) are clearly temp tracks that were left in the game data. Each one is a recording of a man's voice ("Snowy wind!", "Come here, Kopaka... I'm going to kill you... Kopaka...", and "Oh, no! I'm melting!"), complete with corpsing and someone coughing in the background.
The beta build still contains the sound files for removed cutscenes from the alpha build, such as Onua meeting Nobua; Onua using the Kanohi Pakari to push blocks; Onua entering Onu-Koro; the full-length version of Pohatu riding a Kane-Ra; and each Toa performing their respective Takara dance. There is also audio for what seems to be an alternate version of Makuta splitting apart the Toa Kaita, and unused text◊ for Makuta's level.
Both builds contain audio for cutscenes of Gali diving and Pohatu meeting Kopaka, neither of which appear in finished form in either build. Modders even managed to get a working version of the latter.
About a third of the content of The Game was removed before release, including two levels that were heavily advertised in promos. These, or at least their bare models, can partially be accessed from (at least) the PS2 version of the game with some coding. By searching through the game files of other releases, all of the original six Toa's character models can also be exported, even though only two ended up being playable in the game. You can also find some HUD logos that weren't used.
Early Draft Tie-In: Preliminary names for the Rahaga sets: Norik was "Tahkon", Iruini "Lahka", Bomonga "Nuukor", Kualus "Kuuls" and Pouks simply "Puks". The original names can be seen on the backs of the sets' instructions, which were for some reason never edited.
Executive Meddling: The 2005 year was said to be a large result of this. The Metru Nui flashback arc was only meant to encompass 2004, but LEGO had invested so much into developing the setting that they demanded another year to justify it, even though much of the arc was already completed by the end of '04. Most of the decisions made in this year, including Vakama's betrayal, were things Greg Farshtey strongly disagreed with, but were completely out of his hands.
Fandom Life Cycle: Almost got as high as Stage 4, but reverted to 6a almost immediately after the line's initial cancellation.
When the My LEGO Network BIONICLE Campaign was first launched, the tribe of the Hero Agori was not identified. A poll was later held on BZPower to decide the tribal affiliation of the Agori, and Fire received the highest number of votes.
"Nektann" was originally the name for turrets the Piraka used. When a warlord of the Piraka's race was introduced, a fan suggested that the turrets were named after him, and Greg approved it as canon.
The Other Marty: Toa Lhikan has a distinctly different voice in the trailer for Legends of Metru Nui than he does in the actual movie. It's doubtful that it was a placeholder, as all the other voices in the trailer are the same.
Pop Culture Urban Legends: Voriki, Toa of Lightning. In 2001, there was a contest to create a BIONICLE fan website. Voriki was the product of one of those websites, which set up a very elaborate backstory for a seventh Toa named the Toa of Energy. The site went mostly unnoticed until hints of an actual seventh Toa started to emerge; fans rediscovered the website and assumed it was a teaser, but needless to say they were quickly proven wrong. Voriki has become something of a minor meme to the BIONICLE fanbase.
Postscript Season: The web serials continue on past the toyline's cancellation and the main storyline's conclusion in Journey's End. These serials use ideas that were originally meant for the main story before its abrupt cancellation, such as characters being stranded on Bota Magna, and characters searching for the Great Beings.
Real Song Theme Tune: The All American Rejects' song "Move Along" was used as the theme for the Toa Inika. There was even a non-canon Alternate Reality Game with the storyline of the band being kidnapped by the Piraka.
Refitted for Sequel: BIONICLE Chronicles 1: Tale of the Toa was the first publication to show the Toa's battle with the Shadow Toa; this battle was originally going to be shown in the canceled PC game, BIONICLE: The Legend of Mata Nui.
The Naming Day concept was created by The LEGO Group when they were requested to change the names of several characters to avoid a lawsuit by the Maori people, who were angry that The LEGO Group was using words of their language. Some of the names changed were not from the Maori language, but rather from different Polynesian languages.
Carapar only possesses one claw in the set, despite having two in the story. Greg Farshtey once said he can remove one claw in order to hold his Squid Launcher.
The original trilogy movies took great liberties with the toy designs by making their biomechanical characters more organic, more "bio" — they were given hands, mouths, muscles, and in the female's cases, a dose of Adaptational Attractiveness. However some ended up only just very, very vaguely resembling their sets. Now, for the fourth movie, The Legend Reborn, they decided to go the opposite route: making the characters extremely toy-accurate. Ridiculously toy-accurate — some even retained the color-scheme ruining red connector rods. Ironically, the people in this movie were really supposed to be organic creatures with some minor mech-implants. Note that there is a lot of leeway. Many design traits could be interpreted in a myriad of ways. An interesting case is that of Roodaka's "braids": rendered as strands of robotic hair in the movie, as tusks that moved together with her jaw in a video game, and as upward-pointing horns in the comics.
Makuta in his set form wore a double-faced mask — his mask in The Movie didn't resemble either. So when the figure got re-released as part of the special edition Takutanuva set, it came with a special, movie-edition mask which had one of its faces re-sculpted to look like the movie design. This is in contrast to the "Ultimate Dume" exclusive set that came out the following year, whose special mask was designed to go with the figure's aesthetic, which already looked absolutely nothing like Makuta's look in that year's movie.
Greg Farshtey wrote parts of the first comic issue out of fun and then turned them over to his higher-ups. Turns out they didn't have anyone else to write the thing, and as they needed to print the issue as fast as possible, they hired Greg immediately.
The front and back of BIONICLE: Dark Hunters feature Keetongu and the Vahki, respectively. This was due to a printing error by Scholastic. However, the Keetongu error was retconned and explained by Greg Farshtey that it may have been a Dark Hunter "who had some sort of chameleon power" and "appeared as a one-eyed yellow Rahi" in The Many Deaths of Toa Tuyet. The Dark Hunter was later confirmed to be Triglax. The Vahki on the back of the book were explained as well: the Dark Hunters at some point captured some and changed their command to serving them.
Flip Flopof God: Greg originally planned to make Helryx leader of the Order of Mata Nui's predecessor (Hand of Artahka) as well, but after Swamp of Secrets said this was not really the case. Since then, he reserved the right to change his mind on anything not explicitly stated in canon.
Working Title: Boneheads of Voodoo Island and Doo Heads were both used during the theme's development (notably, the internal names for many early BIONICLE pieces are called "Voodoo Claw", "Voodoo Hook", etc.), but the title B4 was also considered.
Writing by the Seat of Your Pants: Farshety has said this is his preferred writing style, at least for the web serials that aren't as connected to the main plot threads.
Farshtey's ex-wife, Jackina, commonly assisted Greg with the BIONICLE story podcasts in offering her voice for the female characters, such as Hahli and Tuyet.
The main BIONICLE logo is an image of the Three Virtues.
The Spherus Magna system is in the shape of the Three Virtues' symbol.
The Kanohi Kaukau was the only of the Toa Mata's Kanohi to have its design computer-generated by set designers—the rest were done by carvings.
Set-wise, the Kanohi Pakari is the most frequently used Great Kanohi, while the Ruru is the most frequently used Noble Kanohi.
The term "Toa Mata" was officially coined after 2001-2002 story arc took place to prevent confusion. During this time, they were simply known as the "Toa" because they were the only Toa ever seen in the story at the time.
Kopaka was the first BIONICLE character portrayed in the comics.
The phrase "play well", LEGO's slogan and meaning of the company's name, is used in Kolhii.
The USA today made BIONICLE Adventures 1: Mystery of Metru Nui #150 on their best-seller list. According to Greg Farshtey's Blog, it is the best selling BIONICLE book.
A special sponge version of the Morbuzakh was released alongside a German BIONICLE magazine.
The Great Kanohi Ruru in Hordika form was the first Hordika head to be seen by fans (through the DVD version of Legends of Metru Nui), although it was white and belonged to a prototype Toa Hordika Nuju set.
The Piraka.com is based in the Piraka Stronghold.
The music playing in the Toa Inika toy commercial is "Move Along" by the All-American Rejects, in accordance with the Free the Band promotion.
A lawsuit was filed against The LEGO Group when a 2-year-old girl was frightened by a Toa Inika commercial, but LEGO won.
In 2007, the BIONICLEStory.com was set inside the Toa Terrain Crawler.
The second Mask of Life code for Command Toa Matoro is former BZPower administrator and former BIONICLE.com Webmaster, Kelly (AKA Binkmeister's) initials. This was done as thanks to all the work he had done to the site.
Gavla's immediate mutation upon becoming a Shadow Matoran was a case of artistic license on the part of the author. In actuality, Mutran would have altered her later.
The Axalara T9 won the French "Grand Prix du Jouet" ("Toy Grand Prize") award in 2008.
Greg Farshtey used Teridax's name as one of his World of Warcraft character's names. He later deleted the character.
Takanuva's possession of his Power Lance and Midak Skyblaster at the time were simply due to artistic license. The book could not be approved without Takanuva resembling his set counterpart, and thusly the weapons had to be included. He did not actually obtain them in the official canon until after the events of The Journey of Takanuva.
Skirmix was named by former BIONICLE.com webmaster Kelly McKiernan.
Nektann's weapon was designed by Kelly McKiernan, webmaster for BIONICLE.com. He was originally intended to have two, but the final set only included one.
The first mask piece to be designed was the Vahi, Mask of Time. It is unique in that it covers only the bottom part of a face, as opposed to almost all other masks, which conceal the entire face. Despite being the oldest, it's not easy to acquire — the piece was to be packaged together with the canceled Legend of Mata Nui PC game, and was later part of a number of promotions or exclusive sets, but these weren't available globally.