The Name of the Rose (1986)

Revealing mistake: When Sean Connery and the others are examining the corpse found in the water, the dead body's eyes blink. (01:01:05)

Character mistake: When William finds the footprints on the ground after the body is found in the blood vat, he tells Adso that they were twice as deep as they should've been because the person who made them was weighed down by the weight of a body. Adso points out that the footprints were going away from the vats, to which William rebukes him and says that the man who made the prints was possibly dragging the body. If that was so, the footprints would not have been so deep, as the person moving the body would not have been weighed down nearly as much by dragging one along the ground. William is a learned investigator who shouldn't have made such an obvious mistake.

Purple_Girl

Revealing mistake: When the dead monk is first pulled out of the blood vat, the others dump water on his face to see who it is, and the body's closed eyes flinch upon contact with the water.

Purple_Girl

William of Baskerville: She is already burnt flesh, Adso. Bernardo Gui has spoken: she is a witch.
Adso of Melk: But that's not true, and you know it.
William of Baskerville: I know. I also know that anyone who disputes the verdict of an Inquisitor is guilty of heresy.

Voice of Adso as an Old Man: Who was she? Who was this creature that rose like the dawn, as bewitching as the moon, radiant as the sun, terrible as an army poised for battle?

Adso of Melk: Do you think that this is a place abandoned by God?
William of Baskerville: Have you ever known a place where God would have felt at home?