I would say Zendaya is not a problem as she looks like someone who could at least be from a nearby region.
However, Lupita as Helen of Troy is illogical as Greeks in that time period had no contact with that region of Africa yet. Also, Helen of Troy is described as having fair skin, so definitely not a Nubian.
Another issue is the armour, the characters are wearing fantasy style equipment which might have some slight resemblance to armour 700-800 years later, but even then nowhere accurate.
And then they seem to be using Viking long-ships instead of the more primitive ships they would have used in 1200 BC.