When Nurse Ryan reports to the Commander of the hospital, she is reporting to Colonel George Beach, who was the actual commander of Brooke General Hospital at Fort Sam Houston where the movie was filmed. That scene was actually filmed in Colonel Beach's office.
The column of troops marching out through the archway was from the 9th Infantry Regiment, part of the garrison at Fort Sam Houston. The 9th Infantry is the only regiment that traditionally marches with fixed bayonets.
It was while doing historical research for the Warner Bros. feature "Captain Blood" in 1935 that producer Gordon Hollingshead got the idea to produce a series of historical and patriotic shorts for Warner Bros. He produced many, including "Soldiers in White" over the next several years, many in Technicolor.
Vitaphone production reels #661A-662A.