Plot hole: After Blaine gets killed and the group hose down the forest, Poncho goes and checks for the enemy. He comes back and says he didn't find tracks or blood "We hit NOTHINGGG." Now, while he would be looking for red blood, he certainly should have noticed at least the glowing Predator blood (made from glow stick fluid - widely used by the military and public alike at the time) easily visible on the large leaf, and deduced that came from something - perhaps the enemy soldier had a glow stick.
Suggested correction: This isn't a plot hole. The plot of the movie isn't broken because of this. It's an assumption that he "should have noticed" the predator blood but he might not have. And if he had, and had discounted it, it would only be a character error not to have mentioned it.
A plot hole doesn't strictly need to "break" the plot to count as a plot hole. The term most often refers to instances when a film contradicts its own sense of internal logic. For example, something happening that contradicts something else that was already established, vital information being left out, or a character acting way out of character for the benefit of the plot. In this case, this absolutely could count as a plot hole.