User blog comment:Aithusa07/List of Plotholes from Merlin/@comment-173.21.72.60-20160312225223

Here you go:

Merlin can detect magic in nearby objects. How did he not detect the pendant that would lead to Uther's demise?

When in the form of Dragoon, he claims to have enchanted Prince Arthur, who knows he is not enchanted, just like Gwen, so why does he think Dragoon is bad, when he knows the wizard never actually enchanted him.

Every time something magical happens, they don't tell Arthur. Why? It is because it would be too easy to sort out all the problems the story has. Back to Uther dying, if Merlin had simply told Arthur he was the wizard who tried to heal his father, and Morganna planted the amulet,etc... I am pretty damn sure Arthur would have upheld his word, and spared Merlin.