Continuity mistake: As Chloe and Clark talk about their feelings the shoulder protector/pad of Clark's backpack switches position with no help from Clark. At first it is more in front and showing more than a few shots later, again with no help from Clark by shifting the backpack, it is more on top of the shoulder and not as visible.
Continuity mistake: As Lois and Clark talk about her leaving, Clark turns to talk to her. Before he turns around the shoulder protector is between his hand and his shoulder and the red side is facing out. In the next shot, even though he made no motion to alter the position, it is now fully on his shoulder with the black side facing out.