Continuity mistake: In Episode 5, "Live Hard, Die Young and Leave A Good Looking Corpse": As Lillie is preparing to cut Zane's throat with her fingernail, she stands with her hand raised above her head for a while. When seen from the front, her hand is balled into a fist with the index finger extended, but when seen from the back all her fingers are extended. The view alternates like this several times, and each time the hand varies between fist and outstretched fingers.
Continuity mistake: When Red Buckley is about to enter Emil Duval's house at night before discovering the black pearl, the lights inside the house are on, but when he finally enters the house they are off. Later when he goes out, they are on again.
Blood Drive - S2-E6
Character mistake: Zayday makes incorrect statements about blood types. She mentions that, since Chanel #5 is type O-, her parents must also be O-; in actuality, they could each be type A or B (genotypes AO or BO, respectively) and could also have Rh+ blood as long as they also carry the recessive Rh- allele. Zayday also says that the child of two O+ parents must be O+, but actually the child could also be O- (again, if the parents carry the Rh- allele).
Chapter Four: The Moveable Feast - S1-E4
Audio problem: When Father Keane is speaking with Mother Bernadette outside, when Mother Bernadette says "The gift doesn't reside in you or me", and "Where you coerce and compel, we use compassion, forgiveness, and patience", her lips do not match what she is saying.
Chapter Twenty-Eight: Sabrina Is Legend - S3-E8
Visible crew/equipment: During the strobe lighting at the very end of series three, with Faustus Blackwood seemingly releasing something evil, it is noticed that during the flashes, it is leaving after effects, showing the shape of the equipment that make the strobe lighting. (00:58:00 - 01:00:00)
The Mind of Simon Foster - S3-E23
Continuity mistake: When the pawnbroker closes his metal gate, he's facing the wire mesh. When the shot cuts, he's instantly facing away from it. (00:10:15)
The Tale of the Whispering Walls - S2-E7
Factual error: Betty Ann is supposed to be telling this story on a Leap Year night with a full moon. While it's necessary for the plot, the most recent Leap Year with a full moon was in 1972, and is calculated to happen in 2048 next.
A Single Piece Was Lost - S1-E10
Visible crew/equipment: When the Gruenaks attack the Scientist a puppeteer is visible to the right of one of the Gruenaks, just before it grabs the bird cage and throws it onto the Scientist's head. (00:28:18)
Audio problem: The zombie chasing the man gets tangled on a wire fence and gets shot in the head. When the bullet impacts his skull he makes a grunting pain noise just like everybody else who gets shots in movies makes the same grunt. First of all zombies don't feel, so how can he express pain, and secondly when people get shot and die they don't grunt, they drop dead. (00:09:30 - 00:10:00)
The Addams Family Goes to School - S1-E1
Continuity mistake: After Mr. Hilliard goes through gate and nears the house, it's really at the real house. A second later, he's approaching the now-familiar front porch on the studio set. This is easy to tell because the layout of the two porches are radically different.
Factual error: There is no way cops would just walk up and open fire on a suspect unannounced, not knowing if he is armed or not, and with an innocent bystander so close.
Revealing mistake: In the scene where Mitchell first visits McNair's van, Mitchell's reflection is visible in the window on the left side of the screen during the shot where he first opens the van door. The vampire lore of the show informs the viewer many, many times that vampires (such as Mitchell) and ghosts cannot be seen in reflections, pictures, or videos (their image "cannot be captured"). The reflection can be seen for roughly 20 seconds. (00:23:20)
Character mistake: When Harlan Edwards collapses and Dr. Arcane tells them to clear his airway, one of the other doctors addresses her as "Dr. Cane."
Continuity mistake: Whenever the Big Brother eye is shown, it is grey and white. But there is a shot of a woman leaving the house in the first episode in which you can see the eye from Big Brother 9 (which is shattered with one red shard) on a platform at the bottom of the stairs.
Other mistake: At the end, when the reflection of burned Lucy still shows her beautiful, Dracula's reflection shows him as he is seen; not old and ugly as in his usual mirror reflections.
Factual error: The British Army soldiers are not wearing British Army uniforms or carrying British Army weapons and some of them have beards, which are not permitted to British Army soldiers.
Deliberate mistake: Identical twins Beverly and Elliot have the exact same beauty mark on their faces, roughly on the smile line directly across from the right nostril. Identical twins don't share features like that.
Continuity mistake: Ruth Deaver is helping Alan Pangborn put on his tie. The camera is facing Ruth's back and we see Alan's face in the mirror. The camera then switches angles to face Alan's back and Ruth's face. Alan's collar which was popped straight up from the first angle is now perfectly down over his newly tied tie from the second angle. (00:24:55)
Containment - S1-E5
Continuity mistake: At the end of the episode, when the bad guy is preparing the syringe of small pox, he follows the usual method of tapping out any air in the tube - when he is shown injecting himself, a large air bubble is back in the syringe (which would probably kill him quicker than the smallpox).
Plot hole: The powerful 'amulet of protection' makes the bullets strike the shooters instead of John. Clearly it works not just against magic and other ethereal threats, but also against physical attacks. So why does he almost get knocked over by a car? True, he isn't seriously injured, but he was thrown to the ground. The amulet should have pulverised that car or bounced it at least two blocks away.