Florence tells Lewis that the Brothers Grimm wrote Grimms' Fairy Tales in the Black Forest which is in Schwarzwald Germany. In reality they wrote the tales in Kassel Germany which at the time of the writing would have been a full day's travel away from the Black Forest.
The goof item below may give away important plot points.
Jonathan and Florence are frustrated to discover their rivals have been resurrected and wonder who could have done it. But there are no other magic users in the film apart from Jonathan, Florence, their rivals, and Lewis. It shouldn't have been a mystery as to who did it through deductive reasoning and only a handful of magic users present.