One thing I never understood about Little Planet is how it's covered with metal and machinery in the opening video, implying this is the "Present", but when you play the actual game the "Present" is your typical Sonic stuff, while the "metal and machinery" more accurately depicts the "Bad Future" areas - but Sonic's clearly going up to the machinery-covered planet from the present, and doesn't start the game off in a Bad Future, but...
Continuity!
Continuity!
Same here. I just assumed that some of the planet was metal, and the other part we couldn't see was okay, because the later stages are mechanical themed anyway.
Judging from the artwork that has just been posted, that's the most likely explanation. The metal cover that chains it to the ground is still half-built, hence why it might look odd in the intro cutscene.





