Tom Stoppard's play Rosencrantz and Guildenstern Are Dead is a perspective flip of Hamlet, written from the viewpoint of the two least important characters who die in the course of Shakespeare's original. Hamlet itself contains a minor but significant fantastical element, the ghost of the dead king.
The ghost does not appear in Stoppard's play, but there is another arguably fantastical element that is crucial to understanding what is happening in Rosencrantz and Guildenstern Are Dead. Although the two protagonists do not realize it (and are indeed extremely confused as a result), they only exist because they are characters in a play. They wake up on morning, summoned to Castle Elsinore, with no clear memory of their lives before that. They travel to the castle, appear for their scenes in Hamlet, and die for no readily comprehensible reason. And yet, even though they have trouble remembering which of them is Rosencrantz and which Guildenstern, they have a sense that, even after they die, they will be back to go through the whole thing again (the next time the play is staged).
That is hardly the way reality works, but it's not really typical of fantasy either. So I am wondering whether it qualifies as on topic here.