LOVE the Mirror Universe host segments, and the Trek references in general. Probably the best host segments as a whole, and easily the highlights of the this episode. Which is a good thing, since they got a real boring stinker of a western.
Doctor F and Frank in the theatre, entering and sitting on the left is a nice twist and cool way to show how things are in the mirror universe.. It's weird hearing their voices giving quips. Dr. F is basically Crow, and Frank feels really out of place. Trace carries most of that segment of riffing, IMO. Frank has his moments, but it's kinda long to sit through. I give them credit for running this far with the joke though, that's pretty cool.
"This is like Gamera vs. Zigra! ...But with cowboys!"
I love that they found this really blah movie with really nothing to it, still got some decent riffs out of it, and then said screw it, lets just do a totally crazy host segment storyline, that'll make up for it!