
Revealing mistake: As the gang drives up to the space-ship diner, cars are whizzing by in the background. When they are driving to the base there's also a clip of a fire truck going down the highway in the distance.

The Magician - S3-E4
Revealing mistake: When Oliver meets Thea at the Grind and Jot Cafe (Which looks unsurprisingly like CC Jitters) you can see the cups on the table are from CC Jitters. (00:20:50)

Broken Link - S4-E26
Revealing mistake: During the fight between Garak and Worf near the end of the episode, a Jefferies tube door is knocked out of its frame to reveal the end of the set - a dark room with a wooden scaffold and various other pieces of equipment. (Slow-mo helpful but not required)

The Night of the Bubbling Death - S3-E1
Revealing mistake: As West drags the body of a bad guy out of the scene, the supposedly unconscious man is holding his head up so as not to have his head dragged through the dirt. A truly unconscious person's head would flop back on to the ground.

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.

Revealing mistake: When Brad wears the sunglasses and holds the pole, you can easily see the string that holding it up.

The Bridge - S1-E10
Revealing mistake: Agent Coulson turns the steering wheel several times despite the car being on a straight street.

Revealing mistake: (Part 4) After Omega takes off his mask and looks in the mirror, when he sees that his physical body doesn't exist he puts his mask back on and screams, but when he shouts, "If I exist only by my will, then my will is to destroy," Omega's mask pops up off his face, and we can see the actor's blackened face as he shouts the last bit of his dialogue. (00:07:10)

Revealing mistake: A straight and level seam connecting the top and bottom halves of the tunnel Spock is crawling through is visible.
Suggested correction: Views of the tunnels made before the creature was wounded by Kirk and Spock appear almost perfectly smooth. It is explained that the creature exudes a powerful acid to dissolve the rock. This tunnel was made after the creature was wounded, so it is logical that the wounded portion of the creature would secrete less acid thus leaving an imperfection as the creature tunnels. This could be a case of incredible attention to detail by the set designer rather than an error revealed.
This correction is too much of a stretch to explain a perfect seam by the wounded Horta. Plus, if the Horta was secreting less corrosive substance, then that area would be less eroded, not more. If attention to detail was paid, then the area would have an outward seam, not an inward one.

Sam: Part 1 - S1-E7
Revealing mistake: When the Ranger first yells "SPD emergency," a piece of Jack's Morpher breaks off.

Knight Rider [Pilot; a.k.a. Knight of the Phoenix] (1) - S1-E1
Revealing mistake: When KITT takes part in the race and goes up on two wheels, you can see that the stunt driver is behind the wheel and that a dummy is strapped into the passenger's seat.

Revealing mistake: The solid brick wall bends like vinyl when Colonel Malloy touches it.

Logan's Run - S1-E1
Revealing mistake: Logan and Jessica commandeer a hover car that floats above the ground, but in shots of the car moving, wheels of the prop hover car are seen.

A. B. and C. - S1-E3
Revealing mistake: In the fight at the end of the B scenario, Number 6 has a small problem. His pants split open in the back. Fortunately, they somehow manage to mend themselves again.

Revealing mistake: When they show the soldiers killed by the Dalek, in both the hallway outside the cage and the large room in weapons testing, they show some casings which were ejected from the soldiers' guns. The casings still have projectiles in them. If used, they would have been in magazines and would never fall out like they are shown.

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)

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.

Confidence and Paranoia - S1-E5
Revealing mistake: After Lister faints, you can see him smirk when the cat sings 'S-E-X, I think I've found it!' (00:08:50)