Continuity mistake: As Clark jumps the fence, to stop Jonathan from falling, you can see Martha is standing in sunshine with the shadow of the barn well away from her. When Clark actually catches Jonathan suddenly Martha is standing in the shadow of the barn.
Visible crew/equipment: As the FBI search the Kent's house, you can see the shadow of the camera as it moves from the kitchen to the hallway next to the stairs. The shadow appears on the right side of the arch between the kitchen and hallway.
Continuity mistake: When the weather vane falls to the ground the rooster portion of the vane gets bent. When Jonathan picks it up and starts to angrily walk away from Martha and Clark it is straightened.