I have to agree with Jeff on the point of not changing data in a production system without external validation.

I've run into that exact situation, a 29 Feb in a non-leap year. I handled it by having an exceptions section in the report, and let the managers and personnel responsible verify the date and handle it appropriately. Turned out it was supposed to be March 29th, not Feb 29th. Made a difference, albeit a minor one. (Nothing so dramatic as Jeff's criminal investigation.) But the thing is, it could have made a big difference, and I had no way of knowing whether it would or not.