Continuity mistake: After Krypto comes around the fence we hear one of the two guys say "You got all the bags out of the truck, right?". The camera then pans over to the van and you can see, under the rear of the van, two gas containers. There is a metal one on the left and a plastic one on the right. Krypto starts to run for the truck and we see the containers again only now the metal one is on the right and the plastic one is on the left.
Continuity mistake: While talking about what to name the dog there are several shots of the dog and the metal chain is gone. Then, right at the end of the scene, as the dog puts his paw over his nose, the chain is back.
Continuity mistake: When checking out the armored car robbery, Clark tells Lois to turn left. We then go to on out of car shot where the big red letters of the GMC that Lois is driving are visible. When the 4x4 skids to halt shot its GMC logo is covered in black tape.
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.
Continuity mistake: Before Clark throws the two bad guys against the side of the barn there is no snow falling at this point. When the shot switches to Krypto saving Hercules you can see that now it is snowing rather heavily. This is far too fast to happen naturally.
Revealing mistake: As Krypto presses the button to open Hercules' cage you can hear the button beep as if it has been pressed but the green light is still on. Earlier the beep which means the button worked also turns off the green light.
Factual error: Clark huddles over Krypto to protect him from the blast of the exploding van. He does not cover Krypto's head before the blast of fire hits them yet Krypto shows no sign of damage. At the very least the fire should have singed his fur.
Continuity mistake: The guide that was with Lana gets killed by soldiers. When the guide is shot you can hear that the weapon has a silencer on it. About a second later we see this still smoking gun has no silencer on it.
Plot hole: In episode 4-16: "Lucy," there is no reason for the criminals to be chasing Lucy on the ski slopes at the beginning of the episode. We learn later that she's been working with them all along; she calls Lois during the chase, and the call is part of Lucy's plan with the criminals. Lucy being chased by the criminals would make sense given the story she gives Clark during the next part of the episode, but it doesn't make sense for what we ultimately learn is the truth. And nobody from Smallville is anywhere near the ski chase, so it also doesn't make sense as any kind of a ruse.
Continuity mistake: As Clark first gets to the bridge at Cherry Hill, the shadows establish the time as either early morning or early evening since the shadows are long. In several shots during this scene the sun suddenly jumps to around noon as the bridge shadow goes from sticking out far to one side to being almost directly under the bridge and the shadow of the semi shortens when Clark is making his super jump.
Visible crew/equipment: Just after Becker starts to chase Lucy there is a shot looking up the hill towards the lodge where she started skiing from. To Lucy's left you can see a fresh pair of ski tracks being made by whatever the camera is on. You can tell these are fresh tracks because there is fresh snow being kicked in the air because of them.
Revealing mistake: As Clark is chasing after the semi-truck with Lois and Lucy in the trailer you can see the Rocky Mountains in the background. Kansas doesn't have mountains. However, Vancouver, where the show is actually shot is home to part of the Canadian Rockies.
Continuity mistake: In the barn loft evil Lex has a kryptonite ring in a lead box. When the camera is in front of Lex he is holding the box so that the lid is pointed towards his thumb. When the camera is behind Lex the box is turned so that the lid is pointed towards the end of his fingers.
Continuity mistake: As the computer says "Subject seeds exposed to radiation" there is a camera shot showing the temperature monitor in the lower right of the shot. In that shot the readout shows the temperature reading is close to 100% of maximum. Then, in the next shot as the scientist says ".absorption level: as expected" the temperature monitor is now close to 90% as we see it climb up to the 98% they were trying for.
Continuity mistake: When Bad Lex is beating up Good Lex in the cellar right before their bodies are joined again, he repeatedly hits him on the right side of his face. However, when the two are finally fused back together, there is a bruising on the left side of Lex's face.
Plot hole: When Dawn enters Clark's body, she slaps Chloe in the face with the back of the hand, and Chloe goes flying. A few minutes later, we see Chloe get up and say that she's fine. Getting backhanded by Clark would make you very far from fine. First of all, Clark can knock someone out just by tapping them on the forehead, as seen in a previous episode. Second, Dawn has no idea of Clark's powers, so she would have used way more force than she actually needed to. The amount of force inflicted from the attack should have caused fatal injuries to Chloe. There's not even a cut or bruise or anything.
Audio problem: As the band is playing right before Clark and Lois enter the prom, the drums are not synced with the music.
