Pneumocephalus, defined as presence of air or gas within the compartments of the cranial vault, can occur after neurosurgery and is typically benign. In contrast, tension pneumocephalus occurs when the pressure of the intracranial air collection exceeds atmospheric pressure, leading to brain compression. The resulting increase in intracranial pressure can precipitate nausea and vomiting, headaches, focal neurological deficits, seizures, altered mental status, and death. Consequently, tension pneumocephalus is a neurosurgical emergency. The accompanying images demonstrate this rare complication and are from a patient who underwent craniotomy for meningioma resection. Delayed emergence and bilious vomiting prior to extubation prompted computed tomographic imaging revealing extensive pneumocephalus and the classic Mount Fuji sign in the axial section.