Kurn's prosthetic nose comes loose from his Kingon make-up. When he talks in the infirmary, you can see it wiggle freely.
When Kurn and Worf initially meet in the airlock the beard on Kurn's left cheek near his chin becomes detached. In the next shot it is re-attached.
Odo is ready to charge Worf with murder if Kurn dies at the beginning of the story. Yet he never gets wise to Dr. Bashir and Worf having Kurn surgically altered, his memory erased and his genetic code altered. Guess that is not a crime on DS9.