Doc Kaiser eliminates Majors Stovall and Cobb as potential blood donors for General Savage because they both have Type O blood while Savage has Type AB, then tells Stovall to identify the members of the group who have Type AB because there is a severe shortage of AB blood. They later stop Sergeant Aaronson from leaving the base because he is needed as an AB donor for Savage. In actuality, the reverse situation is true: Type O blood is the "universal donor" and can be safely transfused into any blood type recipient, and Type AB is the "universal recipient" and can safely receive transfusions from any blood type donor. (Rh factor in blood typing did not become common practice in medicine until after the end of World War II.)