As somebody who knows very little about
Hannah Montana, I'd best look at this as a script in its own right rather than a spec for the show itself!
Things I noticed were largely some SPAG stuff within the dialogue - lots of full stops where there should be commas, for example, and a few sentences that didn't read correctly:
TELEVISION REPORTER
The cattle have been causing a
menace all over the town. But the
freedom one prizewinning cow in
particular named Buttercup -
winning the most bodacious bovine
title the last two years running -
has been the most controversial
causing shock-waves all over the
cattle community.
That doesn't scan right at all! My advice would be to go back and read every bit of dialogue aloud - if it sounds wrong when you say it, then it needs a vtweak - but by saying it, you'll know where it needs a change.
Also, new Acts should start on a fresh page, but that's just a minor formatting thing. Some of the action passages gloss over things a little quickly, too.
In terms of the script itself, though, it seems okay - plenty of zingers, characterisation that seems to be in keeping with what I know of the show (and I say this as someone only vaguely familiar with it), so I reckon it's your execution that needs a bit of work to let the idea come out.