First of all, don't get me wrong, I think you did a great job at mixing, especially considering the short time frame. It's just that some instruments feel a little to unnatural to be believable.
I think the most glaring example are the bagpipes in the Barbarian's theme, where ironically I think the amount of dynamics you added to the track worked against your favour. Even though Uilleann pipes seem to allow for a little dynamics (not an expert!), usually bagpipes aren't a very dynamic instrument. Hearing them play crescendos and decrescendos in such a manner just doesn't feel very realistic.
EDIT: Another example is the brass fanfare at the end of the main theme. While I very much understand you didn't want it to be in focus too much, as a former trumpet player myself it just seems pretty unrealistic to me that brass players could play such a high fanfare without being about twice as loud as the rest of the orchestra combined. I'm exaggerating to make a point here, of course, but I hope you get the idea.