Audio problem: Everybody knows that waterfalls are very loud. However, in the scene at Hakoni Falls, which is completely surrounded by waterfalls, it's silent as a tomb.
Audio problem: When the ice cracks apart at Nita's wedding, a woman in the background says, "It must be a sign", but the movement of her mouth doesn't match the dialogue.
Chosen answer: Probably for just that reason - they were waiting for the right moment to change Kenai back.