When Mrs. Claus opens the door for Abbie, from the back her hair is a markedly different color and texture to how it is from the front (and in all subsequent shots). The back shot was obviously filmed with a stand-in wearing a wig.
Mary Steenburgen's character's name is spelled "Ginnie" every time you see it on screen (the letter to Santa, the check, and the subtitles), but the closing credits spell it Ginny. Elisabeth Harnois is also credited as "Elizabeth Harnois".
When Ginny steps out of the shower to answer the phone and leaves the water running, the tub overflows relatively quickly during the time. All standard USA and Canada tubs have an overflow drain.