More on historical accuracy
Generally I believe movies should be historically accurate enough so as to enable the viewer to suspend his awareness that he is watching a movie and for several hours believe he in another place and another time. Unfortunately this will vary from viewer to viewer depending on the historical knowledge of the viewer. Posters on some of the Wyatt Earp movie boards criticize a particular movie because hats or belts or holsters are from another historical period. Maybe for this viewer seeing the wrong hats on the screen just made it difficult for him to go back to another place and time. Certainly if we saw Wyatt drive off in a pick up truck almost all viewers would find it too incredulous and start trashing the movie.
Regarding GFAOKC, I was not overly concerned that Wyatt was clean cut or that names were changed or that events were inaccurate or out sequence. What kept on coming to my mind throughout the movie was how the hotel rooms were so ornately furnished. I know the set designers wanted period pieces but all the rooms, even Kate's room on the south side of town seemed overly luxurious. I wonder if moviemakers thought that kind of eye candy was appealing to 1950s audiences and would help at the box office?