There's quite a bit of entertaining wrongness about it - sub-saharan Africa is filled with cannibal tribes, and the word "pub" is written in quote marks, presumably because this is "British" slang. But it reaches it's nadir in the quote below (The story so far: Tarzan has been marooned on an island off the coast of Africa called Jungle Island, and has met a native warrior):
This one was Mugambi, chief of the Wagambi of Ugambi...
Please Burroughs. Having invented the Ugambi river, it's not unreasonable that a tribe might take it's name from it, nor that a member of such a tribe might take his name (or possibly title, although it's used as a name throughout) from the tribe or river name. But do you have to be so obvious as to shove all three invented names with the same suffix into one sentence?
(Burroughs has been dead 57 years, so he's unlikely to do anything about it. I, however will attempt to learn from his mistake.)
 More usually referred to by Burroughs as a "savage".