The first thing I see is that the flame shield animation is incomplete. And the third frame in kart boost and fifth frame in the intro don't look right. If the match the last frames on each animation, they might look better.
Other than that, it's a pretty good first try
Edit: And the scorch wheel flames from the credits tag are missing
Other than that, it's a pretty good first try
Edit: And the scorch wheel flames from the credits tag are missing