With respect to the "anachronisms" listed in the "GOOFS" link ...
I like to think they are a matter of the grown-up narrator's slightly muddled memory of childhood events.
Makes me feel better!
Although the movie was supposed to take place in the mid-to-late forties, it sure was reminiscent of the early-to-mid fifties I remember when I was that age. Maybe this is because because many of my early Christmases were spent at my grandmother's house where everything was a few decades older. Also we did have a coal furnace.
This picture is of me and my mom at my grandma's house, 1947 or 1948 I guess -- a bit before my memory kicks in.
Somebody's nuts. I don't know whether it's me or them, but somebody is definitely nuts. I just wished I knew, so I'd know, you know?