In any case, it's a highly unusual looking branch that happens to be shaped like a horseshoe or placed to look like a horse shoe in a movie that involves a spaceship the shape of a......you know what i mean. If its there, its certainly can be used as a scale reference for the ship in post production. I wouldn't expect them to use much of those fake mountains anyway, I expect full CGI and the huge mountain range in comparison is actually that of when Prometheus first got through tthe atmosphere of lv 223.