Just turn it in. What's it gonna hurt? Postage is like less then a dollar. Just tape in a penny. Maybe the guy who reads it will laugh and process it.
I'm gonna say no, unless you go buy another figure in the next couple hours. When processing forms rebates companies look for any reason to deny a claim, I figure giveaways like this would be the same.
I seriously would put a penny in there and mail it. At worst you're down a stamp and you might get the three figures out of it.