I read the British Film Institute's book of critical essays on Groundhog Day (It's on amazon: http://www.amazon.com/Groundhog-Day-BFI-Modern-Classics/dp/1844570320). They talk about how Ramis and Murray didn't want to explain it. The studio forced them too, and one of them sarcastically suggested "a gypsy curse" which of course the suits loved and made them add to the film. IIRC, they intentionally saved shooting those scenes for last, so they could claim they ran out of budget space and skip shooting them altogether. Interesting book though.
What about Mrs. Claus? Saints don't typically have wives. And there's a commercial out now for a (droid, i think?) phone with many closeups of Santa's hands, and he's wearing a wedding ring. Makes sense, but it struck me that I couldn't ever remember seeing Santa with a wedding ring before.