Continuity mistake: When Lana goes to see Lance, who's packing up the serum, you see 5 syringes strapped in, 1 with serum in it. When Lance hits Lex and his case falls open, you can see the 5 syringes still strapped in, but now none have any serum in them. When Lance goes to pick up the case, only one syringe is strapped in, and it's in the wrong spot, next to some blood, and one syringe out of the strap lying in the open case.
Other mistake: Maddie and her father can control only glass, but when at the Talon he uses his powers to pull the diamonds out of the stained glass. Diamonds aren't glass.
Suggested correction: This may not necessarily be true by the way their powers work. Remember, diamonds are a form of rock that are clear. Glass is made from melted sand, which is a ground up type of rock that becomes clear. The similarities between diamonds and glass are enough that it is possible they could still do this.
Diamonds are compressed carbon, not a form of rock. Glass is melted silicon. They're both clear materials, that doesn't mean they're equivalent, otherwise they'd be able to control clear plastic or any number of other things too.
If more explanations of their powers were discussed in the show, one might be able to conclude they do or do not have power over diamonds. However, the script only states they have power over glass, they show no propensity for power over sand itself, or other rocks and minerals. As scripted, this remains as error as it go against what is established.
Revealing mistake: At the beginning, Lional's limo comes to a screeching halt on railroad tracks. The camera is panned out to where you can see this happen. The black tire marks that are supposed to appear from the hard braking are already present, which means there were multiple takes.
Character mistake: Chloe is looking at her digital wall of weird for anyone with camouflage abilities in the past and says there's no match. They act like this is a new power. However, in season 1, "Shimmer", Jeff Palmer had the ability to turn invisible because of a cream he made with kryptonite infused green roses. That should have popped up in her search. And even if it didn't, Chloe should remember the ability to turn invisible because she got the cream on her fingers, which turned invisible.
Other mistake: Jonathan Kent's headstone says he was born September 1, 1954. However, in "Relic", we learn Jor-El visited Smallville in 1961, where he met Jonathan's parents and his mom was pregnant with Jonathan. And we know it was him since Hiram (his dad) wanted to name their son Gene and Jessica corrects him and says his name is going to be Jonathan. Plus, if he was born in 1954, he would have been 25 when he won the high school state championship instead of a more realistic 18 if he was born in 1961.
Visible crew/equipment: Episode 22, Season 5 - "Vessel": Lex returns to the mansion, after being abducted, with his new powers. When he shows Lana by shooting his hand, they start talking by the stained glass window. The reflections in their eyes are supposed to be the light coming through the window, but are actually from a white screen used for lighting. The reflections in their eyes are rectangular to confirm this.
Continuity mistake: In Episode 22- Season 5 - "Vessel": At the start, Lex wakes up and heads towards an open field many miles away from the mansion. They show a camera shot of his face in the field and the sky is grey and cloudy, but in the very next shot the sky has turned blue and the sun is shining.
Audio problem: At the beginning, you hear the horses braying and the dog barking, but you can tell none of the animals are making those sounds. The sounds were added in afterwards.
Continuity mistake: When Zod/Lex pierces Lana's hand, he pierces it at the same level as Lana's head. But in the camera angle immediately following, Lana's head slide downs the wall and draws level with her hand. (00:20:05)
Visible crew/equipment: Martha and Lionel are in the barn when everything starts to fall apart. The camera shot changes from them to a boat falling from the rafters. As it falls there is a visible production crewmember hiding next to the window, holding a hay bale. (00:28:15)
Continuity mistake: While Clark and Zod/Lex are fighting in the field, the blood on Clark's right cheek changes throughout the scene, from disappearing, to smudging, to thick blots. (00:30:00)
Continuity mistake: In the scene between Martha and Clark near the end of the episode, the cut on Martha's forehead switches from above her right eyebrow to her left, and then back again. (00:37:40)
Factual error: The last scene is said to be set in "Iguazú Falls - Patagonia, Argentina." Iguazú Falls are nowhere near Patagonia. (00:40:00)
Continuity mistake: When Chloe and Lois return to where the barn door landed, the shadows and sunshine keep changing between shots. (00:55:35)
Continuity mistake: When Clark blows out the barn doors, they go out at a fairly low angle to the ground. But when they come down next to Lois they drop down straight out of the sky.
Suggested correction: The pieces of the barn and door blown off are on screen for a second or less and don't travel far enough on screen for you to predict their trajectory. They could have easily been moving upwards without being able to tell. The barn door travelled far enough that it would have risen higher into the air.
Continuity mistake: When the barn door nearly hits Lois she is just jogging alongside a clear fence. But when she and Chloe investigate it later, there's a large gate there which was nowhere to be seen beforehand.
Factual error: When Clark is on the roof, and Lionel calls him over to walk to his car with him, in the background as they walk, you can see a building which has the logo of a Canadian bank. Although set in Smallville and Metropolis, Smallville is filmed in Vancouver.
Other mistake: When Clark looks at Oliver's newspaper clipping, there's a story about an AIDS hospice being saved. But the 2nd paragraph on talks about the 2nd meteor shower to hit Smallville that has nothing to do with the hospice being saved.
