I am on the Boat with MIA, in the escalator, and I wanted to get to 3rd floor, but when I jumped on it, MIA got teleported on S2. I have no idea about how it happended, but it happenned. I think there was a monster nearby were I wanted to jump (to get on 3rd floor). Maybe there is a way to use monster hitboxes to get through walls etc?

You need more detail for there to be any validation or possible recreation. Do you have any video?

I have not, it happenned once and I didn't succeed in doing it again.