"Night of the Headless Horseman" is a very odd episode...and very atypical for this show. It's obviously HEAVILY inspired by Washington Irving's story, "The Legend of Sleepy Hollow" and at first I thought is was more tongue in cheek...a funny parody. But as I watched, I saw there were tons of parallels but it wasn't as funny as it should have been. Additionally, it is extremely odd that the episode did not air around Halloween but in the winter!
A goofy Ichabod Crane-like guy, Dorian, is in pretty much the same situation as the character from the Irving tale. Jessica Fletcher has been invited to see him at the Wenton Academy...and for no reason that made sense, Dorian has told everyone that Ms. Fletcher is his mother...not a famous novelist. What follows is a beheading and folks assuming Dorian did it because he was tormented just like Crane was in the original story.
I think this episode really missed the mark. Making it SO similar to the story only would have worked well had they made it more comedic. Instead, it's neither fish nor fowl...not really funny but not really serious either. I personally did not love the episode.