Continuity mistake: When M'Baku challenges T'Challa, the decorations near his neck are in a different position between him facing the crowd, and him turning to face T'Challa.
Continuity mistake: When Ross is interrogating Klaue, there's a shot from behind him and we can see the bug on his left shoulder. When he leaves the room and talks to T'Challa, the bug has vanished, but reappears again shortly afterwards.
Answer: Well he's not literally an uncle to Killmonger, but rather he saw him as a surrogate uncle when he was a kid because he was always by his father's side.
Phaneron ★
And yes, he did know.
lionhead