How is this even possable?

First of all, why would the jaqueta art feature dialogue? Second, Hagrid may not have said it was a Gryffindor scarf at all. Third, and probably most importantly, Hagrid was NOT on the platform with Harry. Harry had been dropped off por the Dursleys on the way to get Dudley's tail removed. Harry was left on his own after that, which was how he met the Weasley family. And lastly, the artist probably thought that up himself/herself. The illustrations are just approximations that go with the story. In my thirteen years as a Potterhead, I have seen three different scar styles for Harry. One is the book scar (vertical, center of forehead). On is the movie scar (vertical, over right eye). And lastly, the one I call the "pillow scar." This version is on an old sheet set I have of Harry playing Quidditch. This scar is horizontal and in the middle of his forehead.
Unfortunately, without the real Harry Potter, we may never know the truth aabout that picture.