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At the end of the game, Spoiler:the game's three previous bosses merge their mechs together to form "The Beastector", the final boss of the game. The mech's design seems to pay homage to a few notable Japanese mechs, such as the Gundam robots from the Mobile Suit Gundam series. Similarities include the distinct V-shape on both of their heads, as well as the use of a beam rifle similar to the ones from the Gundam series.

The way each of the individual mechs morphs into a single bipedal mech is also reminiscent of the Megazord from Super Sentai (Power Rangers in the west).
Contributed by Castle23clash
In one of the stages, there is a mini-boss named Calina. Before fighting her, a cutscene plays where she takes a minute to transform. This is a parody of the magical girl anime Sailor Moon and its transformation scenes.
Contributed by Castle23clash
On the title screen, by holding L, A, Left C & Right C, and pressing Start, it's possible to access a Sound Test mode.
Contributed by SOGESNAKE
According to Treasure's CEO, Masato Maegawa, in an interview conducted by N64.com, there was at a maximum 15 staff members working on the game and an average of 12 throughout the development.
Contributed by GorgonBull35