I don't know if this has been mentioned before, but isn't it perhaps significant that when Terra summons his keyblade, the particle effects surrounding his arm as he does so are nearly identical to the ones generated for Roxas when he is in the data-created Twilight Town? During KH and KH2, keyblades in the 'real' world have always appeared as a flash of light. However, when the Kingdom Key is created for Roxas in the fake TT, you can see the spirals of data forming it into existence. Although Terra's keyblade is fake (no keychain), it is summoned by him in the same way. Could this be a hint as to the barren location where he confronts MX, if we haven't confirmed that location already (the one where the secret endings take place)? Or perhaps some kind of implication that the battle, at least, in the keyblade graveyard takes place in a data-created place, similar to the one DiZ created for Roxas?