Continuity mistake: When Clark lifts Lana back onto the bridge, from a shot from above, we see that Lana puts her left leg onto the bridge into a sitting position. They then cut to a different angle but now both her legs are still dangling and she eventually puts her right leg on the bridge first.
Factual error: When Ian throws the unconscious Chloe over the edge of the dam we see her falling down as Clark falls with her. However, Chloe's body position is unnatural for someone who is falling while unconscious. Her head/body is arched backwards when air resistance should have forced her body to become level/straight.