Deliberate mistake: When the grandfather clock chimes at 12:00, look at it when the clock ticks. It starts at 11:58 but then ticks to 12:00. The clock has somehow ticked 2 minutes instead of 1 minute.
Continuity mistake: At the beginning of the film the boy finds a photograph of the boy and the snowman from the original film, but at no point during the first film was a photograph ever taken.
Continuity mistake: When the boy re-enters the house, the grandfather clock reads 5:10. But when the boy is in his room, the clock reads 4:20. After waving to the Snowman, his clock now reads 5:05.
Continuity mistake: When the boy is shoveling all of the snow, he leaves foot prints from when he walked out the door. But in the shot just before he notices most of the snow has gone, all the foot prints have disappeared.
