So there is no way (as known so far) that you are traveling somewhere and by mistake end up landing on mount Myōboku.
According to the Official Character Databook that is not the case, as the book states that:
(...) it is said that once in a while, a traveler who has lost his way inadvertently gets on the secret path.1
However, even this neither proves nor disproves that it is located in our world. One could get lost and get in some secret path that leads to a region in this world, but getting lost may, just as well, lead you to some secret path that transports you to another dimension.
However, I think it is located in our world, because "Secluded Region" appears written in the page that has info on Mount Myōboku. This piece of info leads me to think that Mount Myōboku is just located in some region that is very well hidden from the outside world. However, it may just as well mean that the "Secluded Region" is some other dimension.
So, basically, it is unknown whether it is located in our world or in another, at least as of now (chapter 623).
1 Page 204, Naruto: The Official Character Data Book