We don't know that Mary rode a donkey to Bethlehem. We don't know what animals were in the stable (actually, we're not even told there was a stable--only that Jesus was laid in a manger because there was no room in the inn). We don't know how long they stayed there or if anyone--including family--besides the shepherds and magi visited them. We know next to nothing about Mary and Joseph, other than Mary being a virgin and them not being married at the time of conception (though it's unclear when they were actually married). We don't even know when Jesus was actually born.
It seems that the details of Christmas weren't what was important (at Easter, we're given the details). God created us, sin ruined our relationship with Him, and He desired a way for that to reconciled. He sent His only begotten Son provide salvation from sins (and the death that results from them) and to give us eternal life. And so as we celebrate the birth of the babe in the manger, we cannot escape the fact that the babe came to die for us all. His life would amount to suffering. And love. And that was His choice--to come to love us and to die for us. Because He desired to.
Most likely no one who was there when Jesus was born knew what lie ahead of him. Did Mary grasp that her son was their at creation and was the one promised of who would crush the serpent's head? Did Joseph understand that his son was born to die? The Magi may have had a notion (after all, they brought Him myrrh which was used for embalming kings). Let us not forget what this babe did for us. That is the detail we must need to know most.