Other mistake: When Clarice is reading the letter from Hannibal, we hear a voice over, however what he says differs from what the letter says, specifically the "your good friend" before the signature, which Hannibal says, but which isn't in the letter. (00:35:35)
Other mistake: Clarice handcuffed Hannibal. Apparently Hannibal opted to amputate his own hand, but the next scene shows officers descending on Clarice at the lake shore. Had Hannibal amputated his own hand, she would still have been wearing the other cuff. She wasn't.
Suggested correction: It's not known how much time passed between these two scenes. At least enough for Hannibal to tend to his wound and escape. It's quite possible she found the key during that time.