IMDb lists The Flag as having been released on October the First, 1927. In the final scene of the film, George Washington and a British officer shake hands. The British officer says, ‘We are on opposite sides today, Sir; but as God is over us all, some day we will be united in a common cause.’ Then there’s a title card that reads, ‘And in 1917 – United in a common cause’ with a shot of U.S., British, and French flags being carried.
I took that to indicate that the film was shot in 1917; but I found the 1927 date when I looked it up on IMDb. It seems strange that the filmmakers would have a scene that appears to be in the pattern of wartime propaganda films, nearly a decade after the war ended. Was there some reason in 1927 that people needed to be reminded that the U.S. and England were allies? After presenting a story about the Revolution, did they feel the need to remind people that though we were enemies once, we were now friends? Or were they just stuck for an ending?