Hitchcock once said something like "plausibility is the province of dull critics," but let's look at what happens in THE REVENANT from the perspective of the Ree/Arikara tribe over the course of the movie (from what I remember, granted):
Before the movie begins the chief's daughter is kidnapped by French trappers for the purpose of rape.
The Ree then attack the American trappers headed up by Domhall Gleeson, Tom Hardy and Leonardo DiCaprio with the precision of World War II snipers, reducing what was a party of 40 to around - and soon less than - ten. They do this because they are looking for the chief's daughter.
Leo's Hugh Glass says they should abandon their boat. They do, which is smart because the Ree are already down river and torch the boat. The Ree then go to the French trappers (who have the chief's daughter) and get horses. Not noticing that the daughter is somewhere nearby.
They then find the remains of Hugh's Indian son and then when they see Hugh by himself in the water, even though there's no way he could have the chief's daughter, decide to try and kill him, because... I mean, I get it, I'd try and kill him too for fun, but whatev's.
I think there's another cutaway to the Ree, but the next time they have a real presence is after Hugh has freed the Chief's daughter, and if we're to believe the French trapper who shows up at the American post, Hugh somehow slaughtered the entire French trapping community by killing two guys (using a pistol that could only have fired one shot at the time) and scaring off their horses, but him having Hugh's water bottle is the tell. It's possible the Ree got to the French as well, I can't tell if that's not clear, or the film's reshoots turned what was meant to be a much bigger scene of Hugh killing the French into a smaller one and then things didn't cut together, or if the script didn't have shits to give.
Geographically, one would think the Ree would run into the French camp and then either find or be able to track the daughter from there, but the next time we see them they're trying to kill Hugh again and send him riding his horse off a cliff.
Side note: When the American hear about a survivor who fucked up the French, they go out to look for this person. 1) Geographically, wouldn't they then run into the Ree first? 2) The dude went off a cliff. So what's the path that would make that easy for them to run into him?
Side Side note: The French kill Hugh's friendly Indian companion. Why? They obviously have dealing with the Ree all the time, or enough that they know that they're both deadly and nearby. Perhaps getting away with stealing the chief's daughter emboldened them, or perhaps nothing that happens in this movie makes any sort of character sense (just a thought). But even if he's a part of a different tribe, wouldn't that stoke the Ree up? Or is it more plotting for the sake of leaving Hugh alone?
Side Side Side note: For a film that made a big fucking deal about shooting in natural light and DiCaprio eating a real raw Bison liver, his character is attacked by a bear and lives. That's fine, that's based on a true story that was mostly ignored for the rest of this tale. But then he also goes down the rapids at one point and jumps off a cliff and falls into a tree a little bit later, but that seemingly doesn't do any additional damage to him, and he's able to go toe to toe with Tom Hardy at the end, seemingly with no noticeable limps or broken bones. Even Rambo would find this implausible.
So then the final moment of the Ree is when Hugh sends the dying but not totally dead Tom Hardy down river so the Ree can finish the job of scalping them they started years ago, and this time the Ree don't try to kill Hugh, maybe because the chief's daughter is there. But then Hugh says some mystical shit about not being consumed by revenge after sorta spending the last ninety minute of the movie supposedly consumed by revenge (this is non-text subtext in that the audience is to assume this, even though nothing in the movie makes it clear until Leo finally says something about it, near the end of the film, even though, you know, he has these visions that are mostly about his dead wife and son and not about his all consuming need for revenge, which he seemingly has at some point) so he lets the Indians, which we suspect that Alejandro G. Iñárritu would not treat like bloody savages, act as bloody savages because they finish what Hugh started.
One wonders if the moment that DiCaprio stares into the camera at the end of the film is the actor asking us if we believe this shit. I don't.
Another sort of nitpick. There's a shot of Hugh, having finally dragged himself away from the camp, seeing water. This is at a point where he's not really walking yet. Where does he see that water from? The top of a cliff. The next shot? Him drinking water. Dude can't walk. Top of a cliff. So, what, two, three days later?
Also, it's made mention that DiCaprio's Hugh Glass is a great tracker and guide. At no point in the course of the movie does he ever use those skills, unless we are to believe his plan was to get Domhall Gleason killed and then use him as bait the entire time. And that's possible, the character could just hate gingers.