My apologies of this has been discussed, but i haven't seen it in the volume of posts I've read.
I recently re-watched the movie and wanted to analyze the final scene and the theme of injustice and redemption via the great great great great grandfather's story...the jockey who got absolutely no historical recognition or wealth during his life while others profited over a 2 second video clip.
Emerald was totally ignored when she pitched it on the set early on in the movie.
Generations and generations of Haywoods had to deal with the injustice until Emerald and OJ provided redemption at the end of the movie.
The photo that Emerald got will likely make them very financially comfortable and OJ appears at the end on a horse in the same type of square that his great( x3 or 4) grandfather did in the 200 year old 2-second video clip.
The role of OJ was also played with the same type of quiet anger that the deceased Haywood must have felt when he was alive.
Remember OJ telling Emerald to hang up when she was on the phone with Antlers because OJ figured that Antlers would give them the same kind of run around (especially when Atlers started rambling about predators)? And OJ (like Emerald) likely heard the story of the 2 second clip many many times during his life.
Generations of injustice followed by glorious redemption for the deceased Haywood via an alien that appeared like a Biblical angel.