Fire Burn, Cauldron Bubble - S5-E13
Factual error: The only instances of "witchcraft" or "witch trials" in America were in Salem, Massachusetts. There were none in Maine or anywhere else. The Salem witch trials spanned 15 months, from February, 1692 to May 1693. Over 200 people were accused of witchcraft, but only 30 were found guilty. Of the 30, 14 women and 5 men were executed by hanging and one man, Giles Corey, was executed by "pressing." Another five died in jail, but none were burned at the stake, which was a punishment unique to Europe.
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.
A Very Good Year for Murder - S4-E17
Visible crew/equipment: After Tony is cured he exits toward his car. A big screen used for lighting is reflected on the side of the car.
Visible crew/equipment: When the sheriff and the mayor meet at the fix-it shop, the filming crew plus the boom mic pole are reflected on the side of the red car.
Night of the Headless Horseman - S3-E11
Visible crew/equipment: When Nate and Dorian fight at the bar they are replaced with obvious stunt doubles with totally different hairstyles.
Night of the Headless Horseman - S3-E11
Visible crew/equipment: When Jessica arrives at the station and Dorian opens the car door, stage lighting screens are reflected on the glass.
Night of the Headless Horseman - S3-E11
Visible crew/equipment: When Nate Findley rides his horse the actor's stunt is very noticeable in the wide shots.
Plot hole: Buccaneer was created by Mr. Vandervelt, so Mr Kimble would never be able to use it to race under any circumstances. (00:42:45)
The Bottom Line Is Murder - S3-E15
Visible crew/equipment: When Jessica rides in the car for the first time, the structure of the filming equipment is reflected on the hood.
Trevor Hudson's Legacy - S5-E18
Visible crew/equipment: When the woman picks up the hitchhiker the filming equipment is reflected on her car.
The Sins of Castle Cove - S5-E17
Visible crew/equipment: When the hairdresser buys a lot of books and leaves in her car, a huge screen and scaffold are reflected on the rear window.
Continuity mistake: When Danny dives into the ocean he's wearing different shorts than he was on the beach.
Plot hole: There were 3 gunshots. 1 from Magnum, 1 from the killer and 1 from the victim. Yet they arrest Magnum with checking the bullet striations. He would be declared innocent almost immediately. (00:17:00)
Plot hole: Barney Kale decides to reopen a case he couldn't solve. Based on the outcome it makes no logic whatsoever. He is the murderer. Why would he bring attention to it put himself in danger? (00:46:50)
Suggested correction: He was being blackmailed by Gary Roberts. He "reopened" the case as a ruse to kill Roberts.

Death Takes a Curtain Call - S1-E9
Revealing mistake: When the cops arrive at supper time at Jessica's door, the background is a blatant painted backdrop. (00:31:45)