I'm a bit surprised that no one has noticed or commented on the use of an authentic flag stop flag.
Much research and some nice custom work went into the green over white flag that is an exact replica of the flags used on railroads from the 1890's into the 1920's to alert train crews that there were passengers waiting. The flags were fairly common in the Mid-Atlantic and New England states were passengers waited in heated shelters until the train arrived. There is one original green over white flag from around 1918 in the Maryland & Pennsylvania Railroad archives and the flags are noted in several rule books from the early 1900's. Were they used in the Western U.S. and did the D&RG have them?