Medical errors are commonly multifactorial, with adverse clinical consequences often requiring the simultaneous failure of a series of protective layers, termed the Swiss Cheese model. Remedying and preventing future medical errors requires a series of steps, including detection, mitigation of patient harm, disclosure, reporting, root cause analysis, system modification, regulatory action, and engineering and manufacturing reforms. We describe this process applied to two cases of improper orientation of a Heimlich valve in a thoracostomy tube system, resulting in enlargement of an existing pneumothorax and the development of radiographic features of tension pneumothorax. We analyse elements contributing to the occurrence of the error and depict the implementation of reforms within our healthcare system and with regulatory authorities and the manufacturer. We identify features of the Heimlich valve promoting this error and suggest educational, design, and regulatory reforms for enhanced patient safety.