16 year old Keisha Castle-Hughes created a minor scandal during the making of this movie when it was revealed that she was pregnant with her boyfriend's child. This meant that while she was portraying history's most famous teenage mother, she herself was actually becoming a teenage mother.
The cast were taught how to use certain tools used 2000 years ago as well as how to build homes, how to press olives and grapes, how to make bread, how to make cheese, and how to milk goats.
This was the first feature film ever to premiere at the Vatican.
In the scene by the Sea of Galilee, when Mary asks Joseph if he's afraid, the script had him responding "No" and then she was also to respond "No" when he returns the question. Oscar Isaac improvised Joseph's confession of "Yes" and Keisha Castle-Hughes followed his lead.
By the time New Line had agreed to finance the film, several other studios had similar nativity scripts under review, so the film was rushed to production for a Christmas 2006 release date, thereby eliminating competition.