Thus far it appears that the two dimensions are identical and not mirrors (right is left, north is south). Yet on the apparent layout of The Crossing, they must likely be mirrors, right? A character enters The Crossing from stage right. He walks through a series of security doors and corridors and emerges in the other dimension. In order for the other dimension to not be a mirror, he must leave The Crossing in the same direction whence he came. There are two ways that I can think of to avoid the mirroring. First, the Crossing transitions from one dimension to the other through a 180 degree rotation on at least one plane (flipping back upon itself or upside down). Second, a set of Penrose Stairs of sorts. I can certainly suspend disbelief on this one point, but it would be interesting to hear other people's ideas.