Audio problem: During the wild boar hunt, they are interrupted by Aleander who says, "Prince Frederick of Saxony. He refuses to surrender Luther to you, Your Holiness," but nothing matches his lip movements. He utters a couple of syllables, at most, out of sync with the two full sentences heard in the movie. (English DVD version). (01:03:15)
Other mistake: When Leo X is hunting a wild pig, a poem is recited which mentions a boar (at least in the german version). But while the pig is running you can see it is a sow (from its longish nose). After the pig is hit, you can even see the teats. In the next shot the sow is supposed to look like a boar: It now has the characteristic big teeth of a boar.
Continuity mistake: When Luther arrives at the monastery for his questioning, he arrives at night, and it is raining very hard. When he is ushered into the room with his mentor, Luther is still wet from the rain, but it is sunny outside the window.
Continuity mistake: After Luther doesn't recant his books at the trial, the Emperor's hand is up near his mouth in a close up shot, and in the next shot we see him in the background with his hand resting on his chair.
Audio problem: When Luther is talking to a friend towards the end of the movie, his friend is 'talking', but his mouth is not moving or moving different than the words being said.