I managed to get myself out of boundaries, and couldn't get back in afterwards. In the area with the thorns and the giant foxes, there's a section where you need to reassemble a statue; I investigated the ground underneath the large statue, and fell through the floor into an area with no background. Afterwards, I could go 'around' the level but there was no way back in, even from the area I originally fell through. Didn't think to get a screenshot, sorry.