The Corpse Flew First Class - S3-E12
Factual error: As the airplane is coming in to land at Heathrow, there is an establishing shot of the wheels down, and in the background there are cars on the road, but driving on the right, wrong for the UK.
Crossed Up - S3-E13
Continuity mistake: When the crime is solved Jessica shows her emergency calling button. The way she holds it changes between shots.
Crossed Up - S3-E13
Continuity mistake: When Grady grabs the diary it swaps between closed or open depending on the angle.
Night of the Headless Horseman - S3-E11
Continuity mistake: In the car, when Jessica is told that she has to act like Dorian's mother she covers her face with both hands. A shot later there's just one hand on her face.
The Bottom Line Is Murder - S3-E15
Continuity mistake: When the cop picks up the dirty ashtray he blows the ash away. In the close-up the ashtray is spotless as if it had been wiped with a cloth or if it were brand-new. First of all, no ash blew away, and second of all, a mere puff couldn't have cleaned it the way it looks.
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.
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.
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.