The fact that Mickey needs to wear a coat that apparently hides his identity. I mean, come on, anyone who's ever met him would automatically know who he is, he may as well just run around with a giant sign above his head saying: "Look at me, I'm in a coat, who could I be with my big round ears and giant nose sticking out of the hood? Oh, could I be a member of Org XIII?"
Big sign.
For Fun:
Mickey walks into the Organization meeting room... place. "Oh my gawd, is that the mysterious other member that we never knew about?" says Demyx.
Everyone inspects the necomer closely. "He must be a member of the Organization, he's wearing a coat, and it's very obvious he's no enemy of ours, with those giant round ears that look exactly like King Mickey, our biggest threat to destroying our plans ears!" says some other member I can't be stuffed naming.
The Org. decide to tell the new member all about their plans and its huge flaws and how easily anyone with a keyblade could thwart the plot.
After this intriguing convorsation, and a few notes were taken for future reference, the new member takes off his hood and reveals himself to be the King. "OH MY GAWD!!!" screams Demyx. "How could we have not known you were the King! It's so hard to tell with that coat on! It completely hides any distinguishing features from everyone!"
Teh Edn!
Oh yeah, then the Organization all die in a horrible fire, 'cause that's what happens when you say pickle in the wrong context.