This short was released before Fantasia (1940), which premiered in November of 1940, yet had many of the same elements, including a symphony conductor in silhouette. The Disney series "Silly Symphonies" was likely another inspiration. Studio espionage...and wholesale borrowing...was rife at the time. Also look for a few nods to MGM's The Wizard of Oz (1939), released the same year.
According to the residents of Vienna, the supposed blue color of the Danube was largely a product of Strauss' 3/4 imagination.
The conductor, in silhouette against sheet music was not using a baton and that was most likely a nod to Leopold Stokowski who conducted without one.