lucy24 - 12:30 am on Nov 9, 2012 (gmt 0)
a 404 can't get passed if you provide a 301 or 302 status code and a 404 can't cause a redirect
A redirect will always be followed by something. The googlebot doesn't go straight there like a human, but it still puts the new name on its shopping list for later.
The OP here is doing a blanket domain-to-domain redirect. So anything that didn't exist on the old domain will similarly not exist on the new domain.
Copywriter, it sounds as if you still have the old site although you're not using it. If there is any pattern to the nonexistent filenames, intercept them before you do the global redirect. A 404 upfront is better than a 301/302 leading to a 404.
Do any of the nonexistent pages come with a referer? Sometimes it's a typo in someone else's site. Sometimes it's just g###s fevered imagination ("no data available")-- which is infuriating but beyond your control.