I believe this is the first episode where the show was taken into a completely different context. They did some special episodes for Christmas but it was still logic and crime based.
I enjoyed this particular episode a lot actually. Especially the theme music.
BUT, the way it ended did not make sense!
It was not the story that went wrong here. The story had no ending so naturally one would expect the next episode to pick up where they left which would mean the end of Murdoch and the whole crew!
Of course it was meant to be a one time thing for a change but to leave it at a one time thing, the ending needs to be appropriate!
In my humble opinion, the writers should have added "and right after the 'kiss' from Dr Ogden, Crabtree wakes up to find a critter on his face" meaning this all was a nice Halloween dream!
So aside from lacking a proper ending, it was actually quite an interesting theme based episode :)