Mobile spinal tumors have been reported previously in the literature, with schwannomas as the most common form. A discrepancy between the location of the tumor in preoperative imaging and its actual position intraoperatively may lead to confusion. The authors present an unusual case of a mobile cauda equina ependymoma. Resection was complicated by cephalad migration of the tumor upon durotomy. Visualization was made possible by engaging a Valsalva maneuver in the patient under anesthesia, at which point the tumor was observed to migrate caudally into the operative field. Observation of this unique pathology is presented as potentially important knowledge for surgeons that might help prevent other unnecessary procedures such as a multilevel laminectomy.