Let's face it. The best thing about this 40-minute short (which is an old 1997 TV cartoon sorta upgraded to the Imax medium) is the 3-D thing. You know: putting on the yellow glasses. Seeing stuff floating right in front of your face. Reaching out and trying to grab it. Kids love that stuff.
And the other appealing aspect of Steve Oedekerk (creator of "Jimmy Neutron: Boy Genius") and John A. Davis's film is that it's for the very young. (Most Imax films reach for an older, family audience.) In this cartoon, a snowman helps himself to a flute in Santa's workshop, but he triggers alarms. Upset, he decides Santa has no monopoly on Christmas and assembles a snowman army to take over yuletide operations. And he captures Santa. The portly old fella has his army, too. In short order, Santa's elf army stands up against this hostile takeover.
Although there may be too much implied militarism for some parents (the snowmen and the elf army fire at each other with weaponry that blasts heat or shoots chocolate sauce, and there are some "Star Wars"-like walking igloos), this is sweet-natured fun for the very young.
SANTA VS. THE SNOWMAN 3D (Unrated, 39 minutes) --Contains nothing objectionable except junior warmongering. At the Smithsonian's National Museum of Natural History.