Revealing mistake: When we see Ian split, his two selves are supposed to be looking directly at each other but they're really both looking slightly to the right. It's hard to focus when there's really nothing there. (00:15:45)
Revealing mistake: When Tina puts the necklace on Clark to disable him, he falls to the ground of his barn. As he is lying there, his collar is very dark, and his shoulder is lit up. Since the source of the green light is supposed to be the necklace, his collar should be the brightest lit.
Insurgence - S2-E12
Revealing mistake: After Lex's employee walks out of the office, Lex gets mad and throws most of the objects off his desk. Prior to this, we see a computer screen displaying something. When the objects go flying off and hit the wall, we see that it wasn't actually a computer screen but a prop that was made look like one. It was just the frame, a piece of paper that served as the display covered by clear plastic to make it look like an actual computer screen.
Revealing mistake: When Pete is on his motorbike they pan to his face and we can see the stunt double. (04:36:00)
Revealing mistake: Clark tries to stop the three guys who are inhaling refined kryptonite. As Clark gets tossed through a window, you can see the explosion of a small charge in the bottom left of the widow. Highly noticeable since Clark hits nowhere near where this charge goes off.
Phoenix (2) - S3-E2
Revealing mistake: When Clark rips the door off the Lincoln, you can see there's no interior panel or door glass.
Revealing mistake: While there was a close up on Clark while he was asleep, you could see a small cut right above his eye, which is impossible if he can't be hurt.
Revealing mistake: Lana and Clark are supposed to be skinny dipping at Crater Lake. When Clark pops up out of the water and goes "boo" to Lana she spins around and splashes Clark for making her worry. As she starts to splash Clark her body comes out of the water far enough to see she is wearing a tan tube top instead of actually skinny dipping.
Revealing mistake: When Nicholas throws the lighter it is supposed to be lit so that it will light the gas and kill Lana but as it flips through the air, before Clark grabs it, the lighter has no flame at all.
Revealing mistake: At the beginning of this episode Lana is supposedly naked. However, when she dives off of the pier, she is wearing a pair of red shorts.
Revealing mistake: When Lionel Luthor visits the Kent Farm and tells the Kents and Chloe that Lex is missing, Allison Mack is laughing when the group is shown from Lex's viewpoint in the barn.
Revealing mistake: When Clark split's the fence at Belle Reve, just before he pulls it apart you can see the breakaway part of the fence. It is a silver color compared to the gray of the actual fence and runs vertically in front of Clark and between where he puts his hands.
Revealing mistake: The computer that Molly takes the hard drive from is shown as having no power cord plugged into the back of the unit. With no power being supplied to the unit the hard drive would not be displaying a picture on the monitor, the monitor itself maybe plugged up but no signal from the computer would be going to it, and we see that the wallpaper on the screen is immediately taken off when Molly unplugs the hard drive.
Revealing mistake: Loder gets scared and tries to get away from Kara. He takes off down the road at a significant rate of speed. Kara uses her super speed to get in front of the car. Loder has to slam on his brakes to keep from hitting her. At the speed Loder was going at he should have either skidded to a stop or hit Kara with his car. Loder is able to stop his car without doing either.
Revealing mistake: When Lucy plays her violin in Lex's mansion, it's obvious the actress isn't actually playing - her fingers aren't moving and the box is out of time with the music.
Revealing mistake: Kristin Kreuk's body double in the shower scene is noticeable. She is slightly larger and differently shaped.
Revealing mistake: When Lana has her nightmare, she wakes up in a room and discovers various people on pedestals, underneath body sheets. During the scene, some of the people under the sheets can be seen lightly breathing, although everyone under them is dead.
Revealing mistake: Clark uses his heat vision to warm up Alicia's cup of hot chocolate. When the drink is hot enough to start giving off steam, the "steam" is not water vapor. Water vapor would be nearly clear and rise straight up from the cup. This "steam" is more likely from a piece of dry ice as the vapor is rolling over the side.
Revealing mistake: When Jason breaks into the bathroom to rescue Lana we see a shot of the shower from Jason's POV. In that shot you can see the steam is coming from the other side of the tub and is flowing up and in. If it had been actual steam it would go from inside the tub out.
Revealing mistake: When Clark throws the two villains against the brick wall at the end, it very flexes as though made of foam rather than brick.
Suggested correction: The guys aren't thrown against a brick wall. They're thrown against the side of an old wood shingled shed.