Revealing mistake: In the scene in which Johnathan shoots Lex, you can see he is gently lowering and raising the barrel of the gun whilst shooting, even though there is a 'bullet-time' effect in progress. Maybe the sequence is shot in real-time, with the actors standing still and the 'bullet' added afterwards? Furthermore, would Lex really move that quickly in relation to the speed of the bullet?
Revealing mistake: At the beginning of No Mercy - Season 5 Episode 19, 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.
Revealing mistake: In the early scene with the baby, there are a few overhead shots of the parents and child. It is clear that in these shots a fake baby was used - he is completely motionless, even though he was moving arms and legs before and after and is crying. (00:02:00 - 00:03:15)Phoenix
Revealing mistake: As Sheriff Ethan pulls up there is a reflection on his driver side window. You can see the police department shield on the door and the door handle reflected on the driver's side window. There were no other police cars there so it was probably reflected off a mirror used to help light the scene.
Revealing mistake: Lana and Clark are supposed to be skinny dipping at Crater Lake. When Clark pops up out of the water and goes "boo" to Lana she spins around and splashes Clark for making her worry. As she starts to splash Clark her body comes out of the water far enough to see she is wearing a tan tube top instead of actually skinny dipping.
Revealing mistake: The Smallville Torch that Clark looks at online is the exact same one last seen by Lex two episodes ago in "Craving." This wouldn't be a problem, but Clark remarks that this Torch is "another scathing editorial," indicating that it is new, and Principal Kwan complains that parents have been calling all morning, which means that this issue of the Torch was published either this day or the day before. Prop department must have been saving money. (00:08:40)Phoenix