Well done, very fun. Straightforward story, and I agree with those here who feel that Scotty and the others who turned did so a bit too quickly. Tom Haberkorn seems to have been working on his voice for Spock; I hope it wasn't just for his portrayal of mirror-Spock. Seems to be a bit more gravitas to him.
Vic Mignogna's Kirk portrayal can border (but in my opinion, hasn't crossed over to) parody, but in this case, it serves him in the over-the-top miror-Kirk. Mirror-Kirk should always be chewing scenery!
Chuck Huber's return to McCoy is hard to judge based on the little we've seen, but his brow-raise and quip sold me for now. I'd say just get him a wig though!
Another solid effort; looking forward to what's next.