Although I'm at a loss to think of a good example, I think there are things that show up in movies that are there simply because they are something current and not something done intentionally (or left out intentionally), without the slightest bit of propaganda. Smoking might be a good example, although in some movies, the hero was never shown smoking or drinking. There were references to the end of prohibition in a couple of Three Stooges shorts, which I'm sure were there to make possible a joke or two. Was there ever any propaganda involving the end of prohibition?