At the end of the opening credits, just after "Screenplay by David Mamet" and before "directed by Ridley Scott", look at the right hand side of the screen - you can see Hannibal's face drawn by pigeons.

In the scene where the pickpocket is trying to get Hannibal's fingerprint on his bracelet, the cinema in the background has a poster for Gladiator - also directed by Ridley Scott.

In the brain eating scene, the piece of brain Ray Liotta eats is actually a piece of cooked chicken.

Not a mistake, but something I just noticed on about the 5th viewing. In the very creepy 'I've given very serious thought...to eating your wife' bit, during the ominous pause in the middle a fly crawls down the back/side of Anthony Hopkins' head, then flies around a bit. Can't be helped, and barely noticable, but it does wreck the mood a bit.

Not a mistake, just a bit of irony....there is a vegetarian cookbook on top of the refrigerator that Hannibal has Clarice trapped against, also a guide to Southern Cooking.