No, you're misunderstanding. The return here is NOT an HTTP status code. It is an internal apache thing. It happens to be 404, but that's just a convenient number the apache devs chose. The HTTP status code is something you set with $r->status, not the return from the sub, and it is Apache::Const::HTTP_NOT_FOUND (which is 404 and you really could just use the number), rather than the one you're using here.