Visible crew/equipment: Near the beginning of the film while Clarice is being interviewed, we can see a black T-shape during a shot of the floor. This is shown to be an actor's mark, as someone steps right into it a few shots later. (00:12:58)
Revealing mistake: During the scene in which Krendler shows the fake Lecter postcard, look closely and you can read the line: "Sounds like him to me" although this line is part of Krendler's speech, and not part of the message itself. Forgetting your lines, Mr. Liotta? (01:21:55)
Answer: In the book it says that Clarice had caught Buffalo Bill before he could. It said also that is why he hated her early in the book.