For those curious, the donut shaped universe shown isn't what the theoretical universe model actually looks like,

What it represents is an "asteroids like" geometry of a two dimensional universe where exiting one "side" brings you to a corresponding point on the other.

The proposed donut geometry of the universe is what's called a 3-roid or 3-tauroid, which is basically the same idea as the asteroids like 2D universe but for a prism instead of a rectangle. Meaning that our ability to return to the starting point is based on the fact that we are moving along a 3-D "surface" of a 4th dimensional object, the way the Asteroids ship loops back to the start by moving across the 2-dimensional surface of a 3-D geometry.

Part of me wonders if this means that the actual boundaries of the universe are at 0+ and 0- along the W/A axis in 4-D space, and if that means that every character who has some power related to moving in 4-D space would actually just fall out of space and time if they ever tried using their abilities for real.