You are viewing a PDF for submitted form data. You have fields that were present on the form when it was originally submitted that have since been deleted from the form builder. When you open the PDF link, the fields removed from the form builder may no longer display in the submitted form data PDF.
The PDF link will update based on the fields currently on the form under Site Explorer > Forms. If a field is deleted from the form builder, it will no longer display in the PDF view of submitted form data.