The Salazar episode is definitely covered by poetic licence, unless the author explicitly claims historical accuracy.

Both poetic licence and suspension of disbelief must be earned by offering a story that makes good sense in itself. In good fairy tales, the reader or listener is told in advance about the premises of the conflict, e.g. the exact powers of a wizard or a magical object. Starting from that, logic and psychology must apply. If anything unexpected happens, it must be explained in a way that does not appear "far fetched" within the given setting.

Authors of entertainment fiction are typically in a hurry, so that construction errors abound, often much more annoying than mere errors of fact. The film industry can afford to be more careful; they employ specialists of "continuity".

Great literature is yet another thing.