Revealing mistake: All of the exterior shots of Jessica and Hagarty are wide shots with very obvious stand-ins. Jessica is thinner and younger, while short-haired Hagarty's double is younger, chubbier, and has long hair around the nape.
Dead Letter - S6-E6
Factual error: Unlike the Connie Kowalski character in this episode, real insurance investigators are not trained in arson investigation. Insurance investigators search for evidence of fraud relating to insurance claims. Arson investigators are professional firefighters who have had extensive additional training in arson investigation.
Who Killed J.B. Fletcher? - S7-E14
Factual error: Bremerton, Washington is not a hick town as depicted in this episode (it is the home of Puget Sound Naval Shipyard, a US Navy installation that employs 14,000 people) and the people there do not have southern accents.
Factual error: At the end of the episode after Wayne is shot, there is a brief shot of the outside of the hospital where he has been taken. The sign outside the hospital says Dalesboro, Ohio. Why would someone shot in coastal Maine end up in a hospital in Ohio?
Factual error: "Witches" were burned at the stake in Europe, but not in America. In America, they were hanged.
Tinker, Tailor, Liar, Thief - S8-E15
Revealing mistake: In the second close up shot of Nigel Atkins lying dead, after Jessica drops her Harrod's bag in the chair, it is obvious he is still alive as you can see his pulse on the side of his neck.
Factual error: Celestial navigation can determine one's position on the earth's surface to within about one mile, not precise enough to give the location of a buried treasure. It also requires more than a sextant. It requires tables published in a nautical almanac (which is updated each year), charts on which to plot lines of position, and an accurate chronometer that is set to the precise time at the Prime Meridian (Greenwich Mean Time).
Factual error: When Buck's body is found, his blood is red when it should be brown due to oxidation after how much time has passed.
Continuity mistake: When the episode begins, Jessica is having a meeting with Sally Wilson, who hangs a bag over her shoulder. A shot later, her bag is down and she is hanging it again.
Audio problem: When Buck walks to the bar downstairs and meets Mrs. Oates, the sound of their footsteps is that of tiled floor, but they're walking on a rug.
Visible crew/equipment: After Seth drives Jessica downtown, lights, crew, and filming equipment are reflected on the car window.
Continuity mistake: When Jessica is having dinner, his glass swaps between full or almost empty depending on the shot.
Audio problem: Several times during the episode, when someone is walking on a rug, the sound of footsteps is that of a hard tiled floor.
Visible crew/equipment: When the cop grabs the coffee pot, a filming crew member with blue trousers is reflected on it.
Character mistake: When the corpse is taken out of the water, he moves his mouth.
Audio problem: The cabin floor is carpeted, but the footsteps heard are of a hard tiled floor.
Character mistake: Ottawa is misspelled "Ottowa" on Nicholas Jenson Davis wanted picture.
Revealing mistake: When the episode ends and Jessica drives the buggy, she is replaced by a very obvious stunt double with a wig that not only does not resemble her hairstyle, but it's grey as opposed to her light blonde colour.
Continuity mistake: When Danny Kincaid is at the beach, he is wearing green shorts when he is taking his shirt and shoes off, but he has blue and black shorts on when he goes into the water. (00:19:00)
Continuity mistake: When Danny dives into the ocean he's wearing different shorts than he was on the beach.
