I used to enjoy debunking the Christmas myths. You can start with the nativity scene and begin removing the pieces that don't even appear in the gospels (like the animals and the stable for instance). We tend to add the wise men from Matthew's account to the shepherds from Luke's, though the former gospel suggests that the (more than one, but not necessarily three) wise men came some time after Jesus birth and visited Joseph and Mary in their house. It's all too easy if you just read the scriptures and are able to temporarily suspend what you think you know in the story.
However, this is perhaps the perfect time to recognise a third path between a constrictive, literal interpretation that is increasingly difficult for modern people to sustain and dismissing the Christmas story altogether. John Dominic Crossan, who is perhaps the pre-eminent historical Jesus scholar in the world today, says of the Emmaus road tale in Luke 24 "Emmaus never happened and Emmaus always happens". Crossan rightly asserts that truth can be found outside the realm of historical veracity. The same is true of Christmas.
Very few people believe that Jesus was really born on December 25. Most scholars don't even think we got the year right - between 4 and 6 BCE is more likely. However, the danger of getting bogged down in debates about whether particular elements of Christmas were 'true' or not is that we miss the primary point - God was found in Jesus. Now that takes some explaining and although we might do it differently now to the way they did it in the first century, we are seeking to capture that same experience. So enjoy the donkey and the star for a moment for what they are: pointers to an incarnational presence that changed the world.