When Jesper finds himself trapped inside Klaus's barn, he's wearing a cape and scarf. After he lights an oil lamp, the cape and scarf disappear.
When the first batch of children arrive to send their letter to Klaus, one in the middle is holding an envelope in his left hand that says 'Eirik', with 'Mr. Klaus' below it. In a shot from behind the children, this envelope is suddenly seen in the right hand of a child that is far more to the right than he should be.
Just after Jesper is explaining to the kid who got coal that only good children get presents, he slams open the lower part of his door, which passes right through two children standing in front of it.
On the tapestry that depicts the feud between the Krums and the Ellingboes, 'Ellingboe' is misspelled as 'Elingboe'.