Hello, thank you for the comment!~
We spent a lot of time trying to get familiar with Lua and Love2D during this so we weren't able to get everything working the way we wanted. The branches and small ledges were intended to be as you described but we ran out of time.
As for falling through the floor, that is no accident. It is there to basically make you upset. There were supposed to be visual changes on entering a hidden path such as that one, but again, we ran out of time.
We are unsure why you had to download something else to play the game, but we added the missing file in case anyone else runs into a similar error. We have since fixed the error preventing you from playing the rest of the game as well. So please go back and enjoy the rest of the game.
Thank you.