Factual error: In the 5th season episode "Lexmas," Chloe says she needs Clark to deliver the Daily Planet's Toys For Tots contribution because of a Teamsters' Strike. However, the Toys For Tots program is run by the United States Marine Corps Reserve, and collection and distribution is handled by Marines and Reserves. The Teamsters have nothing to do with it.Captain Defenestrator
Continuity mistake: As Chloe is trying to get Clark to help her deliver presents Clark says "Chloe, you didn't have to go there." Right before he says this the two of them start rounding the corner to go down the next hallway. As he is saying the line they are back in the first hallway and start rounding the corner again.
Plot hole: Clark is delivering presents for Chloe. In the overhead shots looking down on Metropolis he super speeds from building to building and he only spends like one second in each building before going to the next one. This doesn't match what is shown while we see him leave presents by the various trees inside the apartments. In those interior shots he spends 5-10 seconds in each room. The overhead shots are not sped up. Not only do these times not match up but he would also be slowed down to open the doors or he would constantly be breaking them down.
Revealing mistake: During the scene with Lana hemorrhaging after giving birth, and Lex being escorted out, we see him pounding on the door and disturbing the blinds, yet in all other shots of hospital rooms in Smallville, the blinds are on the insides of the rooms, not the outside of them.