First vertical row of pixels on the far left of the map visible on the far right
From Worms Knowledge Base
Pixels from the first vertical row of the map can be seen on the absolute right. They cannot be destroyed or damaged from the right-hand side, nor do they have any mass. As the first row is destroyed from the absolute-left side of the map, the pixels will also disappear from the right (although they will be replaced with the "behind" texture).
This phenomenon also affects the mountain layers - the first vertical row of pixels from the absolute left appears at the absolute right of the map.