The autopsy scene contains at least 8 errors. Among them, the body was fingerprinted without collecting evidence under the victims fingernails, and the ink would have destroyed the evidence. You cannot get fingerprints off a body in that condition.
When Clarice visits the entomologists to identify the moth pupa, they say while examining the chrysalis that it must've been specially raised from imported eggs and fed "honey and nightshade". Deaths Head moth larvae, like most caterpillars, eat only vegetation; the adult moths eat honey.
The ring of sweat on Clarice's sweatshirt as she is running on the Quantico course in the beginning of the movie covers her body almost from shoulder to shoulder. When she gets called into Crawford's office, it is significantly smaller.
During the autopsy scene, they remove the bug cocoon from the victim and insert it into a small jar with the bug antenna pointing to the bottom of the jar. The next next shot shows Clarice pouring fluid into the jar with the antenna pointing up.
Clarice runs a course on a Marine Corps Base in Quantico, VA, which is also home to the FBI Academy. The Endurance Course is about 5 miles long throughout the Quantico highlands, in the Marine part, not the FBI part. At the cargo net obstacle, she was nearly at the end of the course, about 2-3 miles from the FBI Academy. A road is to the left on the screen, and nothing but miles of woods is on her right, when the FBI agent comes out and says that Crawford wants to speak to her. It would've been faster and more logical for her to finish the course, not run 3-4 miles back through the woods to the FBI academy.
When Catherine Martin drives into the parking area, the killer looks right into the headlights of her car while wearing night-vision goggles, but he isn't blinded. Goggles of that time might have been permanently damaged. Newer goggles have automatic protection mechanisms.
West Virginia State Police uniforms have been forest green since the early 1900's. Their vehicles are blue, with Old Gold and the State Seal on the door. The director asked the WV Department of Public Safety to use some State Police in the movie, but he didn't like the colors of their uniforms. When he asked them to change into the Brown uniforms, they refused and left the set.
The film refers to "iron sulfide, also known as 'fool's gold'." Iron sulfide, more specifically, iron (II) sulfide or FeS, is an unstable chemical compound that's usually brown or black. The fool's gold they refer to is commonly known as pyrite, and its proper name is iron (II) disulfide (FeS2). Even if Agent Starling and Dr. Lecter knew enough about chemistry to know the chemical composition of fool's gold, she would have known it as either pyrite or iron disulfide.
The biologist identifies the moth found behind the murder victim's soft palate as Acherontia styx, the Deaths Head moth. The Deaths Head moth used in the poster is actually Acherontia atropos. (A third Deaths Head moth is called Acherontia lachesis.) While A. styx is native to Asia, as identified by the biologist, A. atropos is native to the Middle East and Mediterranean.
Crawford tells Clarice that Miggs died by swallowing his tongue. Literally swallowing one's tongue is impossible. However, an unconscious person's tongue may sag backwards and block their airway, leading to suffocation.
During Clarice's first visit to see Hannibal, she wore a skirt with belt on the waist when she was in Dr. Chilton's office and before entering the final corridor leading to Hannibal's cell. The belt was gone when she entered the corridor. She probably had to remove her belt before entering the maximum-security area, particularly if it had a metal buckle.
Lecter correctly refers to the moth pupa as a "chrysalis". Many moths, including the one in the film, pupate inside a chrysalis. "Cocoon" refers to a type of silky case spun my many types of insects, not just moths.
Jodie Foster has blue eyes. When she is at the funeral home she has a flashback and sees her father in the casket. Clarice as a little girl is supposed to be going to see her father in the casket. The little girl's eyes are Hazel, not blue. Adult Clarice could wear colored contacts.
When Clarice is talking to Buffalo Bill in his back room, a moth is filmed landing on a cotton reel. After the moth has settled, a thread is visible attached to it. Presumably the shot was filmed in reverse, and the moth was yanked off the reel.
When Clarice is researching Lecter in Quantico by reading old newspaper articles on microfilm, the same text regarding developments at some vague governmental conference appears over and over again surrounding the Lecter articles in all four separate newspapers she views.
During Lector's escape, the "swat" team arrives and jumps out of the police car at the courthouse with their Ithica 37 shotguns. All of them are shown chambering their rounds except the the officer on the right, who pulls back again on the fore stock and asks "ready?" That should've ejected a shell and left the gun unloaded.
When Clarice crawls under the door at the self-storage shed, the camera pans along the large unlighted interior. Although self storage units typically do not have windows, sunlight pours through windows on the far wall.
When Sgt. Pembry is preparing to handcuff Dr. Lecter to the bars of his cell while bringing in his requested second supper, he has Lecter sit with his back to the bars and his arms thrust behind him in order secure the shackles. It's obvious that Dr. Lecter has been waiting for a fair amount of time between his first meal and his second serving because his drawings and magazines are spread over the entire desktop surface. A closeup of the Lecter's arms shows red, discolored wrists.
As Hannibal escapes, he kicks the cell door onto the guard, causing the door to be in between Hannibal and the guard. Yet in the very next shot, the guard is right in front of Hannibal so he can bite him.
At the end of the movie, when Clarice Starling is searching Buffalo Bill's basement, she approaches a door with the doorknob on her right, indicating it would open to her left. When we see the door open from the opposite side, it opens to her right.
In the cut to the scene outside the Memphis Police headquarters, after Lecter has escaped, an ambulance with Hamilton County tags roars across the screen and stops. Memphis is in Shelby County, 400 miles west of Hamilton County.
Although a human skin garment is implied, most of the sewing examples are blatantly wrong to anyone experienced in tailoring. For example, while Clarice stands in the first victim's sewing room, she recalls the diamond-shaped pieces of skin removed from the girl found in the river, and thinks of the darts commonly used to reduce fabric bulk in the waistline, making a garment more fitted. The problem is, the dart shapes cut from the skin resemble the unwanted pieces of fabric that are wasted. Later it shows him sewing on one end, single thickness. He's not sewing anything to anything else, and he's using a piece that is typically cut off and discarded during garment construction.
After Hannibal escapes from his temporary cell in Memphis, the police believe Dr. Lecter is cornered, injured and unconscious, on the top of an elevator. The officer is told to shoot him, non-lethally, in order to determine whether he is alive or not, and wounds him in the back of the knee with his police issued 9mm handgun. The body showed no reaction to the shot, so they decided he was dead. Even a dead limb would move away from the direction of the shot.
When Buffalo Bill cocks his gun, the shadow of Bill's hand holding the gun is clearly visible on Clarice's back as he raises it to shoot her. The basement is supposed to be pitch black, so there shouldn't have been any shadows.
When Clarice is in the pitch black basement, searching for Buffalo Bill, he points a gun at her head through his night vision goggles. The gun makes a shadow on her back, which wouldn't happen without light.