Penetrating chest injuries can lead to diaphragmatic injuries, which are often missed easily on initial assessments, especially in patients with polytrauma. We are usually more focused and biased towards other evident, immediately life-threatening injuries. The fact that clinical and radiological findings are subtle, especially on chest X-rays, which is sometimes the only investigation performed, highlights the importance of using higher imaging modalities in stable patients and that a clinician should be suspicious of this entity with the corresponding history. Intervening in such patients with the placement of intercostal drain can contribute to morbidity and mortality, as in our case, by causing inadvertent injury to the herniating structures. The case report briefs the same and emphasizes that thoracic injuries, especially penetrating ones, should ring a bell and should be carefully investigated further before the intervention.