Revealing: 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.

Plot hole: In the episode Onyx, Lex's alter ego holds him hostage in the wine cellar claiming that when they were kids, Lex accidentally got locked in down there. In the pilot episode, it is established that although Lionel had the castle shipped over from Scotland brick by brick and built, they never moved into it.

Plot hole: When Lex gets onto the plane at the beginning, the doctor performs a procedure on him that she says will purify his blood (due to him drinking the poisoned brandy at the end of series 3). She states that Lex needs to do this procedure every 72 hours to stay alive, yet after this, it is never mentioned again. Surely if Lex had been cured (or even if he hadn't) it would be explained what will happen to him.

Continuity: When Clark drops the photo of Jonathon, the frame breaks and the photo can be seen separate from it and face-down. When Martha finds it later on, the frame is still intact and the photo is perfectly positioned face-up inside it.

Factual error: There is a snow pattern on the Quicktime player after Chloe's message to Clark finishes. She would have recorded in on a camcorder, so there wouldn't be any snow pattern, it would be a blue or black screen. The only way there could have been is if she recorded it, put it on VHS, then copied it back onto a DV tape, then transferred it back onto her computer, but there's no reason for her to do this.

Revealing: Kristin Kreuk's body double in the shower scene is noticeable. She is slightly larger and differently shaped.

Continuity: When Jason starts knocking on Lana's door, the clasp from the door chain is all the way to the left. The camera cuts to Lana in bed. When it cuts back to the door, the clasp is now all the way to the right.

Continuity: When Kal-El/Clark pushes Martha away her hands are down around her chest. The shot changes, as Kal-El builds up power to fly, and now Martha's hands are spread out away from her body.

Continuity: While Martha reads to Jonathan, as he is in a coma, the light on his hands change. In the shot from the right side of Jonathan's bed his hands have only a normal level of light like from a small table lamp. The shot changes to look at Jonathan from the doctor's point of view and suddenly Jonathan's hands are very brightly lit like from a spotlight. No one changed or turned on any other lights between shots.

Other: Lois digs up Chloe's grave site to unearth her casket. It is obvious that the casket is not buried six feet deep. You would think, will all that is going on, that LuthorCorp would have at least buried the casket deeper to deter inquisitive eyes and maybe throw in a few scattered bones for good measure.

Continuity: As Lana saves Lois from Trent, as Lana first starts to spray the pepper spray/mace the camera is behind Trent and the mace is coming out in a mist. The camera jumps to behind Lana and now the mace is firing in a steady stream.

Plot hole: During the flashback scene showing how Chloe and her father survive the house explosion it is explained that there was a team in the house and they grab Chloe and her father and rush them into a tunnel just seconds before the house explodes. However, as seen in the episode Covenant, Chloe is standing next to the door and Chloe's father is more than 15 feet away from her when the door of the house shuts. As soon as that door shuts the house explodes so unless this S.W.A.T. has Clark's super speed ability this would be very much impossible.

Continuity: In the episode "Skinwalkers" the Naman separating from Segeth glyph is colored red and blue In this episode, with no explanation whatsoever, it is black and white.

Continuity: As Trent and Lionel talk, while Lionel is in the hospital bed, when the camera is behind Trent his shoulder and neck are barely illuminated and is in shadow as the camera is looking down on Lionel. When the camera is looking up at Trent, even though he has not moved, his shoulder and neck are now brightly lit and shows no sign of a shadow.

Continuity: During much of the conversation between Clark and Lana, while in the caves, you can see the cave painting that matches the tattoo on Lana's back is behind her. Then, towards the end of the conversation, she is still standing in front of Clark and during the scene has not moved from that position yet, once she sees the cave painting behind Clark she walks over to it and turns around to face Clark, which puts the painting behind her even though it was already behind her before she moved.

Continuity: As Lana and Lex are talking, as Lana says "Actually, umm, I came by because.". In the middle of her going "umm" there is a camera change. Before the change Lana has her right hand on the arm of the seat. After the change she now has her right hand scratching her head.

Continuity: Gabe Sullivan's headstone is on the right side (if you are looking at the headstones) of Chloe's in the previous episode. In this one it's on the other side.

Audio problem: When Clark talks with Lex in the house where he found the two dead bodies,just after Lex finished his phone call, Clark says to Lex, "You looked at me straight in the eyes and told me she was dead," and then the shot changes to Lex. Clark's lips are still moving even though his line is over.

Continuity: When the mirror falls on Lana and shatters on her, you can see that there are bleeding cuts on the left side of her face. However, for the rest of the episode, there are no cuts on the left side of the face (where they should be) but there are cuts on the right side of her face.

Continuity: When Lois is strapped down on the cosmetic table, as she is struggling to free herself, the position of the strap that is holding her down over her chest, keeps changing how far on/off it is, on her breasts, between different shots.