Plot hole: 1-6 "A Gummi By Any Other Name": The Changing Hat has the habit of tranforming its wearer at the mere mention of a name (or even a species type, as seen before when Sunni accidentally transforms into an ogre). However, when Calla impersonates Igthorn and faces off against him, she loudly says the name "Toadwart" and doesn't transform.
Plot hole: 5-10 "Princess Trouble": The catapult King Jean-Claude accidentally triggers smashes the siege tower on which Calla and Marie are fighting over Sunni. But since Jean-Claude's catapults are all aimed at the walls of Dunwynn, how come it smashes the siege engines on its own side? Neither catapult nor tower were moved before the misfire occurs.