Continuity mistake: The string of Christmas lights which the Peanuts gang remove from Snoopy's doghouse are flashing multi-colored lights. After they "re-do" the little tree, at first the string of lights is not on the tree. In following shots, the string of lights appear, but they are now steady-on yellow lights.
Continuity mistake: When Charlie Brown and Linus leave the auditorium to go and get a Christmas tree, they are shown exiting the same yellow building which they had exited from at the beginning of the show. Later, when Charlie Brown exits from the same auditorium, bringing the little tree with him, he exits from a red brick building.