Other mistake: 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, with 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.
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 mistake: 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 mistake: 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.
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 mistake: 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.