Continuity mistake: During the bridge collapse scene, when Olivia is crawling on the beam, she is first seen on the part of the beam that is closer to Sam. Almost instantly afterwards, she is on the part of the them that is closer to Molly. The space between the two beams increases significantly between the two shots as well.
Continuity mistake: In the premonition right near the end, you see the truck hanging over the bridge and that is how the poles and that sheet of metal kill two of the main characters. Yet when they run to the end of the bridge, the truck is not hanging over the edge.