Continuity mistake: When Lana undresses before jumping into the lake, she kicks all her clothes right beside Clark's feet. But in the shot where she dives off the end of the pier, all of the clothes are piled well away from Clark.
Continuity mistake: When Clark goes to give the flowers to Sarah, her uncle answers the door. The first shot is of the uncle through a flyscreen door, which he opens. We then see a shot of Clark outside the door, and then the uncle opens the flyscreen door a second time.