Rootie, thank you for another interesting photo! Notice the flagpole in the background. At first I thought it might have been from car owner Lucy O'Reilly Schell and her international Maserati effort. But now I don't think so. From the photo it looks like the three flags are for the nationalities of the drivers in the 1940 500. Obviously, there were plenty of Americans. But there were also two Frenchman (Le Bègue and Dreyfus driving for Lucy) as well as a driver from Argentina (Raúl Riganti). So the three flags (from top to bottom) are from the United States, France, and Argentina. I guess in 1940 the 500 was still trying to live up to its official name as the "International 500 Mile Sweepstakes".