Cholecysto-antral fistula and gallstone ileus are rare complications of a common disease, gallbladder stone (GBS). This fistula is developed as a prolonged complication of cholelithiasis in which the gallbladder adheres to the adjacent antrum, and a stone erodes through the wall. Among the variety of cholecystoenteric fistulae, the cholecystoduodenal fistula occurs more commonly than the cholesysto-antral fistula. In this scientific study, we present a 98-year-old male patient who came to ER with a complaint of abdominal pain, vomiting, and constipation for five days. He was vitally stable and had normal laboratory results. The plain abdominal X-ray showed dilated loops with excessive gases. His computed tomography (CT) abdomen with contrast showed small bowel obstruction secondary to an impacted gallstone at the distal jejunum, fistulous communication between the gall bladder and the antrum, and pneumobilia. Our management included endoscopic retrieval of a single gallstone from the second part of the duodenum followed by open surgical enterolithotomy, partial cholecystectomy, and closing of the fistula. Despite our case sharing many aspects with the available literature, our case, to our knowledge, is the first case of ileus gallstone occurring in a 98-year-old patient. Cholecysto-antral fistula has not been widely published in the literature. The offending gallstone presented along with the radiological Mercedes Benz sign which does not present in all cases of GBS. Typically, the obstructing GBS stops at the terminal ileum, but in our case, it was dislodged in the distal jejunum with no previous biliary symptoms. Finally, we were able to remove another single GBS from the second part of the duodenum during the preoperative upper endoscopy. The clinical diagnosis may be missed due to the vague presentation of symptoms; hence imaging, especially of the CT abdomen is crucial in establishing the diagnosis, moreover, performing an upper endoscopy could have diagnostic and therapeutic benefits. In cases like this, the main surgical intervention should be to address the bowel obstruction, and cholecystectomy with fistula closure may be added if the patient's condition is stable with minimal inflammation and adhesion.