Pace it up
That long scene where Luigi and Mario are talking needed some major fixes. For a start you can't have people just reading text for that long, you need to animate them walking around, or have some different camera shots (panning or zooming), perhaps flash some images across the screen to illustrate what they're talking about or at least cut out any necessary dialogue and keep it short and tight. (I suggest all the above)
These suggestions applied to most of the animation. You can be both dramatic and fast paced. Make the text bigger, and make sure you stop all sounds at the end.
Other than that I look forward to the full thing.