The thing is Rambo had survived far worse than a few local police and more importantly was a fictional character. The revanent was based on a true story, but got the Hollywood treatment. DiCaprio was good, he ate raw fish and meat and climbed inside a real horse apparently, all in the freezing cold, it was a good acting performance (its got the feel of Hollywood saying he's been in a lot of good films we'd better give him an Oscar for this) but the film was just a bit meh.
I think the biggest point of bullshit is that the bear attack happened in the summer, it was a mother with 2 young cubs apparently, but that fact got changed in the film.