These ambitious visual effects would have made the setting and characters more unique. But LoMN is a low budget film rushed to meet a deadline, and it already juggled way too many ideas anyway. It's a shame but also understandable that many effects couldn't be realized.
Several elaborate animation effects were planned but ultimately simplified or removed from Legends of Metru Nui, presumably due to budget/tech/deadline issues. They include kinetic display screens forming the shape of Turaga Dume during public announcements.
The Dume-Makuta reveal was also planned to be done with a mirrored kinetic display. I'm not sure how that would work or why a mirror would be designed like this, but it partially explains the conceptual origin of the mirror seen in the film that ripples like liquid.
@Arsonkaizer They were a bunch of minions who combined with Makuta to make him bigger, at least in the 2003 story treatment of the unproduced Lhikan and Nidhiki origin film.
https://t.co/HQZgM1XGeu
One odd thing in the draft is Makuta saying "we" and "our" even though he's technically alone in the room. But knowing that the originally planned 3rd movie was going to reveal Makuta as a combiner made up of multiple beings, referring to himself in plural sort of makes sense.
Bionicle 2: Legends of Metru Nui is a funhouse of half-realized ideas, mid-production rewrites and other compromises. Some scenes make more sense when compared to early script drafts, storyboards and the novelization. What do these tell us about the confusing Dume=Makuta twist?
@KumataJDG Probably, though the leaked treatments and script predate the Shadow Hand. Makuta just absorbs the DHs and Nivawk with shadow tendrils and he uses a scepter for the rest of the story. The SH ability was probably added so he could both absorb and attack without using a tool.
Some fans theorized that Makuta had been talking to another member of his Brotherhood via the mirror who happened to have the same voice as him. But the film follows an earlier version of canon where the Makuta Brotherhood were the components of Makuta's body, not other Makuta.
The simple canonical explanation to this mess is that Makuta has been talking to himself in two voices, portraying both the fake Dume and his real self, and he even projected his own true eyes onto the mirror because... he just did.