I would make the ship shoot off into the night at the end, rather than slowly tween out. Make sure your squash and stretch the ship and add a trail of light or something, to add a bigger sense of speed if you decide to make it shoot off.
The expressions are okay, but some subtle blinking wouldn't go a miss, while the ship drops them off. They look too static and flat standing there.
Its too limited to really give any feedback on. Maybe that's one criticism...its too limited.
More frames in the electricity would make it much smoother. Also make it faster. It would look more realisitc.
Add some lighting effects to the ship as the electricity sparks and dissipates.
Having electricity wrap around the ball of light as it grows and roll around it would make it have more depth to it.
Add lighting effects to the people. Shadows flashing changing diectino on the ground etc. (check out the opening scenes to terminator 1 and 2 for inspiration)
More variation on the effects are needed as it is the only real piece of animation in this.
(check this out:
http://media.photobucket.com/image/lightning%20ball%20animated%20gif/XxSeanxX13/Ball_Lightning.jpg - make sure you reference a lot of relevant things when designing or animating)
Oh and your opening credits takes way too long for such a small animation. A skip button would be nice here.
Speaking of the logos, they are pretty small and its hard to read the text, and also ILLSTRATE should be spelt ILLUSTRATE.
And make the Hit State of replay the entire REPLAY button, not just the written text. That can be annoying.(draw a box the size of replay text in your hit test frame of the button)