When Harold confronts the knight mocking Arn, the ale-stain on the knight's tunic, sizable and visible in all previous shots of him, vanishes.
When Arn goes to pick up the tunic and helmet he dropped, the next shot of either shows him picking up the helmet, which Harold takes. But in the next shot of them, the tunic has reappeared in his hands though neither of them picked it up a moment before.
When Rowanne tries to warn Arn about Harold, the sleeves of her mostly fern green dress are included in that color, each with a marigold or goldenrod ring at the end. In the next scene, when Arn tells her she's wrong, Rowanne's dress sleeves are white. After that, her sleeves are back to the original color as most of the rest of her dress again.