I’m just using a normal toon shader with UV mapping for the textures. At first, I thought the problem had something to do with the textures, but the same thing happens when I do an un-textured render.
Hmm, definitely looks like render artifacts to me, how about if you try a different shader?
If that removes the artifacts then there’s probably a bug in the toon shader.
If so, then specifying you’re computer specs & OS info,
blender version & what renderer you use would be great.
If the render’s from blender internal the bug should be reported to the tracker respectively.
are your normals facing the right direction or do you have multiple faces trying to fill the same area? have you tried deleting the area and putting the faces back on?