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 Pink Panther holds the "Here We Go Again" sign when hiding in the bear-skin rug, the eyes of the bear are completely different to the ones seen a few shots earlier.