Visible crew/equipment: When Jeremiah has just stabbed Clarke in the barn, after he goes down the steps and the camera follows him walking away you see the back of one crew member's head and then a second crew member's, starting in the bottom right of the screen. Just before scene cuts to black you see the first crew member turn his head to the left. (00:26:46)
Revealing mistake: When Pete is on his motorbike they pan to his face and we can see the stunt double. (04:36:00)
Visible crew/equipment: When Martha and Jonathan are talking about Lionel's job offer in the kitchen, a boom mic can be seen in upper left corner of the screen.
Revealing mistake: When Clark gets hits by lightning whilst trying to save Eric, you can see that Eric is a stunt double.
Factual error: When Lionel is leaving the prison, there is a bus unloading convicts as he walks past. No prison in the world would ever unload inmates and release an inmate in the same area at the same time.
Visible crew/equipment: When Tina, disguised as Lana, throws Pete against the lockers, you can easily see that it's Pete's stunt double.
Continuity mistake: When we first see the meteorite tattoos on Wade Mahaney, they are all green. When Clark sees Whitney's tattoo, it is plain black. It was also faded, which means it's not a fresh tattoo. Whenever Clark runs into the other guys, he feels the effects of the meteor rocks, but never when he is alone with Whitney.
Continuity mistake: When Phantom Clark finds Lana on the balcony with her phone pressed against her ear, she lowers the phone down to her waist twice between shots.
Continuity mistake: In the previous episode, "Slumber," Clark wrecks the farm truck by falling asleep while driving. The car has massive damage that, at a minimum, would be extremely expensive and time-consuming to repair. Realistically, though, it is completely totaled. In the episode "Perry," the truck is again in brand new condition, like it was untouched.
Other mistake: After Clark enters the phone booth, he begins to change out of his red shirt. The phone booth is mostly frosted glass, but it is possible to make out that Clark only becomes bare-chested before the next shot when he comes out of the phone booth with the blue shirt on. (00:02:14)
Continuity mistake: When Lex starts learning about Veritas he sees the symbol on his office window, but that was never there in all the 6 previous seasons.
Other mistake: When he takes Lana to the Fortress of Solitude, Clark squeezes a rock and when he opens his hand we see a perfectly cut diamond. Problem here is that in the real world, diamonds don't come out of the earth already cut and shaped. (00:04:20)
Continuity mistake: When Chrissy kisses Troy in the beginning on the episode, it takes him a few minutes to age and die. Later in the episode, she kisses Russell and in a matter of seconds he is old and gray.
Suggested correction: When she kisses Russell, she kisses him longer than she did Troy. We even see him age faster the longer she kisses him, indicating the length of time she spends absorbing someone's youth, the faster they age and die.
Factual error: Clark lifts Chloe's car by the back. He is only holding on to the very back left portion of the car, yet while he's turning it, the car is completely horizontal. The front of the car would buckle since it weighs so much and isn't being handled by its center of gravity.
Plot hole: When Clark uses his heat vision to heat the metal door handle to prevent Desiree from escaping, he only heats one handle. I know that things were happening fast, but it wouldn't have taken him that much more time to heat both handles, which he should have done since there is no way he could have known that she would have tried that particular handle.
Plot hole: Though it fits the general plot of Davis always being first on scene, in the real world no on-duty paramedic drives the ambulance alone. There will always be a minimum of two EMTs per ambulance, one to drive and one to tend the patient. The only time a paramedic or other EMT will be alone is if they arrived on the scene in their own vehicle.