It could be a basic mercator projection, which essentially is just a flat, distorted view of a round world. We're not seeing the full picture there, so it's hard to say. But there's obviously world "above" and "below" the image we're seeing here, so my guess is that one side is closer to the equator and the other is close to the pole, and for whatever reason we're just not seeing the pole. It might be more accurate to say that we're not getting the full picture of the hemisphere instead of calling the world flat, but that's just my opinion.