I have never undestood why garden path sentences are interesting. They can always be rewritten to make more obvious sense. Its like saying theres a way to take any sentence and remove some words to make its intended meaning confusing. I dont personally find this interesting, just frustrating that the author didnt take more time to use punctuation or more words to convey explicit meaning.
I think it shall be interpreted like this: The creature who fell was the horse (that was previously raced past the barn). I.e. it was not the barn that fell.