Why does Castle Oblivion look so small?

[Xidon]

Castle Oblivion is small couse it is a holograph room from Star Trek that Organization 13 stole >.>

Nah not really, but it did make a illusion of worlds which Sora visited, it was probably something like the Data world made my Ansem (the TT data town).

 

[Spic Steve]

It's a video game, it doesn't have to be proportionate to anything.

 

[Nazo]

it might be just a trick of the eyes that it is small

Probably. Castle Oblivion was like the most confusing place in the KH universe, so it's probably just an illusion trick.