For several decades researchers have searched for possible inefficiencies in sports gambling markets. Most profitable strategies have failed to produce profits over the long run. The one consistently profitable strategy that has been studied extensively involves taking advantage of differences between contracts offered in different regional gambling markets. The main purpose of this paper is to explain why and how these differences affect the profitability of wagers. I describe two ways that one could take advantage of these different contracts, loosely defining one of these opportunities as "arbitrage." This paper examines the circumstances under which inter-market gambles in the NFL can be made with an expected profit. Of course, it is expected that as with all arbitrage opportunities, such circumstances are expected to be rare and short-lived, except when betting against a local team.