Factual error: In the scene where the top of Paul's skull and scalp are removed, the scalp looks normal. In order to remove the skull and scalp in such a manner, the blood supply to the scalp would've been completely severed. Without a blood supply, the scalp would've quickly discolored, and certainly wouldn't look nice and normal.
Factual error: When Clarice is being questioned about the fake postcard, they are supposed to be in Washington DC, but the James Monroe building located in Richmond, Virginia can be seen through the window. (01:24:56)
Factual error: Clarice shoots the guys in the barn, then handcuffs the fat one, but as she is walking away his arms are spread too far apart to be cuffed. When the pigs come in, we see him dragging his buddy using only one arm with the other at his side, again impossible when cuffed.