Character mistake: In the very first scene, in the first shot you see a sign in Spanish that says "NO PASE por orden del departamento de arquiologia". The correct Spanish word is arqueologia.
Character mistake: We see in a flashback (so, early 1600s) the protagonist with his mother in Ruen, back in motherland France. She tells him she is praying to St. Joan (d'Arc; they are in front of a statue of hers). Joan d'Arc wasn't canonized until the 20th century. You could argue that in the eyes of the laymen she was already considered a saint. However, her son does not object and considers her a saint as well, doubling down on the statement even later on in Quebec when he does not have to humour his mother, and he is a Jesuit. He obviously should know better. (00:35:25)
Character mistake: After Santa gives the children new clothes, Ray says that he and the mother can now raise the 9 children. The mother points out that they only have 2, but he points to the group of orphans to include them. However that makes only 7 children.
Character mistake: One of Jack's fellow producers starts choking on a pickle, the other knows this yet says it's a sandwich she's choking on.
Character mistake: Cynthia Kellogg comes forward to voluntarily give information about the James Urbanski case. Detective Nealy tells Kellogg, "As a matter of procedure, I have to inform you of your rights." Kellogg says she didn't do anything so doesn't need a lawyer. Nealy replies, "This is your right" and proceeds to inform her of her Miranda Rights. Miranda warnings are applicable to suspects/defendants who are in police custody (under arrest) and about to be interrogated, not voluntary witnesses. (00:03:02 - 00:03:57)