Pancreatic and gastric heterotopia is an uncommon congenital anomaly in which gastric and/or pancreatic tissue is found outside of its anatomic location. In the majority of patients, lesions are found incidentally because they tend to be asymptomatic. However, lesions may become symptomatic when inflammation, obstruction, and bleeding occurs. Depending on tissue size and location they can harvest a landscape of nonspecific symptoms, causing a delay in diagnosis. Heterotopic tissue of either gastric or pancreatic origin have been reported in literature, however the presence of combined gastric and pancreatic heterotopic tissue is exceedingly rare. We report a case of an 18-year-old female with polypoid gastric and pancreatic heterotopia and focal intestinal metaplasia of the gallbladder with clinical findings of acute cholecystitis. In this literature review, we synthesize the clinical significance, histopathological features, diagnosis and management of pancreatic and gastric heterotopic tissue.