Revealing mistake: Season 5 Episode 18 "Spark of Life": when they show a closeup of the badly-burned woman during her debridement, it can be seen that even though her eyebrows and hair and, in fact, 90% of her skin has been burned away, she still has long, full eyelashes.
Revealing mistake: 1967: Barnabas and Vicky are talking in Collinwood's foyer when a great deal of noise starts interrupting the scene from backstage. You can hear coughing, several bumps and crashes, shouts, and finally, a fire extinguisher going off. Meanwhile, the distracted actors are completely blowing all their lines - but the unstoppable taping goes on.
Revealing mistake: With Marshal Mars in pursuit, as Ray drives his pickup, he holds the steering wheel with his left hand, and his stiff prosthetic right arm is down at his side. When Kate grabs for the steering wheel, in the side exterior shot the stunt driver is quite noticeable, as he grips and turns the steering wheel with his good right hand/arm. (00:30:40)