I guess since its only the opening to Naruto that they didn't put much thought into it. In the previous opening when they show Tobi and the Jinjuriki when you see what little portion of skin trough his eye holes both sides are scarred even though only one side is scarred
it is a preview of the episodes that will show. ( if the opening features naruto fist bump kurama, it means that we are close to see the episode where naruto will actually fist bump him.) I don't know if i'm making sense there