The famed director Frank Capra (known for It Happened One Night and Mr. Smith Goes to Washington, among others) chaired a military organization called the U.S. Army Air Force First Motion Picture Unit during the war. Jack Warner, head of Warner Bros. was also high in the unit's command structure. They employed many of the most famous men in American film, including well-known stalwarts of animation like Chuck Jones and Mel Blanc (famous for creating and voicing Loony Tunes, among other projects). They also employed Frank Thomas, one of Walt Disney's "Nine Old Men." The Motion Picture Unit produced training films for servicemen as well as propaganda to be released in theaters. So, in many cases these films were produced by the government by filmmakers who had been drafted into the Army and thus were subject to military authority (for example, future President Ronald Reagan was a 2nd Lieutenant during the war and assigned to the unit). In other words, they received very close and clear instructions on what to say. Capra answered directly to Army Chief of Staff George Marshall, so the unit's activities were directed from the top of the command, primarily based on the Army's needs for training and morale-boosting films.

CUNNINGHAM, DOUGLAS. "IMAGING/IMAGINING AIR FORCE IDENTITY: "HAP" ARNOLD, WARNER BROS., AND THE FORMATION OF THE USAAF FIRST MOTION PICTURE UNIT." The Moving Image: The Journal of the Association of Moving Image Archivists 5, no. 1 (2005): 95-124. http://www.jstor.org/stable/41167189.