Ok, pay attention during the scene at the Hawaiian bar (right before Ben Afflack and Josh Hartnett start fighting), Ben Afflack's character pours himself a drink, then we see him using an empty glass as a plane to retell his adventure in Britain to another character (it is clearly seen that there is no drink on the bar). Josh Hartnett's character enters and Ben Afflack hold up a drink to him, grabbing it from the bar where we just saw there wasn't one.