Corrected entry: The inconsistency occurs in the scene where Marcus confronts and kills the chief of the Seal People, thus recapturing the Eagle. As he is about to kill the chief, he asks him where he got his father's ring. Up to that point, the only way Marcus could communicate with the British tribes was if Esca interpreted for him. This was indicated in the film by the fact that the Romans spoke English (representing Latin) and the Britons spoke another language, which was subtitled. So as the film sets it up, Marcus and the chief do not speak a common language. Yet in this instance, the chief apparently understands Marcus's question with no problems. And yet, when he gives his answer taunting Marcus about his father's cowardice, he speaks his own language (subtitled) which he knows Marcus does not speak. Indeed, we know Marcus did not understand what he said, as he asks Esca several times afterwards what the chief said about his father. So when did the chief suddenly become able to understand Marcus's language, and if he can actually speak it, why not reply in it when taunting him?