Released today, Continental Airlines is offering 250 bonus OnePass miles for tickets purchased on continental.com using a debit or credit MasterCard. The offer is valid for U.S. residents only for tickets purchased now through June 30, 2011. Continental has offered a similar promotion in the past, and there are some date range discrepancies in the fine print, as well as claiming the bonus to be 500 miles, so we’ll see what actually happens. Still not a bad way to rack up some incremental miles.