In Songs to live and die by, Keith visits Lucas in a dream and shows him what would have been if Lucas was not the guy he is. In the dream, it shows Keith wearing what he wore when he was shot. However, when he was shot, he was wearing a green undershirt, but in the dream, it shows him wearing a white undershirt.
When Brooke shows up in Peyton's bedroom to tell her about Lucas and Haley, she says, "There's been an accident," after she enters the bedroom. However, the same scene is at the end of the previous episode, and she did not say it then.
When the medic is giving Lucas CPR, he is pumping his stomach, not his chest where his heart would be. Pumping his stomach would do nothing in the case of Cardiac arrest.
When the EMT is doing CPR on Lucas, in addition to doing it on his stomach instead of his chest, the EMT also checks his pulse 3 times in less than a minute. He does a few compressions, checks the pulse, does a few compressions, checks the pulse, and once again does a few compressions, and checks the pulse. This is not how CPR is done.