Revealing mistake: After Rygel realizes that he can loosen the soil with the dumped gruel, it cuts to John and Aeryn as they approach the Tavlek camp, and when Aeryn tells John, "I am going to take out every last Tavlek. No survivors. No mercy. Now give me the oculars," John holds up the syringe (with Zhaan's sleep mist) that Aeryn had given him earlier, and we can see "DG-4" engraved on the side of the gun, revealing that the prop dept used the model DG-4 aluminum air blow dust gun to play the part of the syringe.
Best Day Ever/The Gift of Gum - S4-E20
Revealing mistake: When Squidward says "I suppose if you haven't fixed my clarinet, the concert would have been a bust", Sandy's tail is the same color as her suit.
The Last Of The Starks - S8-E4
Revealing mistake: At the beginning when all the dead are burned, we see a close up shot of a dead guy still breathing.
Revealing mistake: During the fight scene at the end when Buffy is fighting the demons you see her throw one of the demons off the platform. If you watch him fall you can see him land safely on a conveniently placed mat. (00:38:10)
Revealing mistake: When Sookie finds Dawn dead, in the close-up of Dawn's body, you can see the actress' pulse at the base of her neck. (00:50:55)
Double, Double, Toil and Trouble - S4-E4
Revealing mistake: As Serena gets hit by the pie her real blonde hair shows underneath, also, she wears minimal make-up for the only time.
Revealing mistake: Before Jason Dean is shot outside the penthouse, Phoebe is waving her hands trying to convince him that the world is not real and you can already see blood on her fingers.
The Funeral - S2-E44
Revealing mistake: The support wires on the bat are visible as it flies out the window.
Food Fight - S1-E6
Revealing mistake: When Pudgy Pig is standing outside of the food packaging plant, a human hand can be seen sticking out of Pudgy Pig's wrist. (00:15:30)
Clash!! Sonic VS Knuckles - S1-E5
Revealing mistake: Right at the end of the episode, when Amy is telling Knuckles he should apologize, Amy has two right hands.
The Bermuda Triangle Crisis - S2-E4
Revealing mistake: When Wonder Woman drops a mine into the water, she's supposed to be dropping it into the ocean. However, you can see a drain plug of some sort in the background and the "ocean" is obviously a pool, or similar.
Revealing mistake: In the wizards versus werewolves special, it's painfully obvious Juliet is a stunt double when she fights and grows her wings.
Tabula Rasa - S1-E3
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)
Revealing mistake: When Xena 'dies', her pulse is checked, and they can't find one, yet you can see her pulse in her neck. (00:30:30)
On the Road - S2-E1
Revealing mistake: As Cassidy, Tulip, and Jesse are trying to outrun a police car, another cop car enters the road in front of theirs with tires squealing. There are tire skid marks On the Road before the cop car enters, indicating previous takes of the same stunt.
A Sentimental Journey - S1-E19
Revealing mistake: Dialogue in the episode specifically mentions the A2 and A282 roads near Dartford, Kent - the actual roads used were the A1 Barnet by-pass, Galley Lane and Well End Road. The error is revealed by the sight of a road sign that appears just as the Austin Princess Limousine turns on the the main road - the sign shows that the car is not turning on the the A2/A282 near Dartford, but the A1 at Barnet some 40 miles away.
Revealing mistake: In the first shot of the scene where Emma and the others arrive in Storybrooke in their cars, on the left side of the screen, you can see a sign behind a branch. It says "Steveston Museum and Visitor Centre." Steveston is the name of Canadian town which doubles as the town of Storybrooke on Once Upon a Time. (00:07:00)
Remy Rides Again/Hassle in the Castle - S5-E10
Revealing mistake: In the episode Hassle In The Castle, in the hall of Infamy the name plates are either scribbles or they're just blank.
Revealing mistake: "Alan a Dale": Lady Mildred rides side-saddle. But when Gisburne gallops away with her, some shots reveal that the stunt woman riding the fast-moving horse is astride it full straddle. Her skirt is blown back just enough to see a brief glimpse of the stunt rider's real leg on the horse's right, and the fake pair of legs in side-saddle position on its left. For just a moment, the lady appears to have three legs. (00:20:00)