Continuity mistake: Charlie Brown's Christmas tree is never the same. When we first see it, it has three branches. Later, when he's carrying it, it has four branches. Then, when he tries to decorate it and it flops over, it has six branches.
Continuity mistake: When the janitor goes up on the elevator, he is holding his broom in one hand and a bucket in another. When he sees the Pink Panther wearing a tiger's mask, the bucket has disappeared, and when he reaches the top of the elevator, the bucket is back again.