Spoiler:
well spike got kidnap, and another male pony appears, we also see horse drawn carriges...and horse drawn-horse drawn carriage...and pinky pie is random...lol
I am upset by the lack of barrels in this episode... Also I am so happy they avoided the stereotypical Native American speech patterns for the bison. Plus I loved the reaction to Pinkie Pie's plan.
Oh no people on the internet are complaining about something... These are multi-colored talking horses if they influence your views on ethnicity in any significant way you have bigger problems. Also I hate when people go on about how the crew should have done this or that to make things more authentic, without even considering the time given to animation production is limited. Plus I love how the person who wrote that sounds like they are so perfect and better than everyone yet can't tell the difference between bison and buffalo.
The author's tone is grating, but the article has a point. There is some pretty classic fantasy-setting racefail going on in MLP if you take the latest episode in tandem with the Zecora episode. Pointing this out does no harm.
The problem of otherness is probably just not an angle the production team considered. This is usually how racefail material finds its way into fantasy fiction. It's probably something they'll think about in the future.
(I can't seriously believe the MLP team is insensitive to the idea that they're making a show for a very young audience that's still internalizing ideas about race and will draw impressions from basically everything it sees and hears.)