Take Ben's "Oh, don't worry, he'll be all right," and have it play over the shot of the severed arm on the floor of the cantina.
In the Falcon cockpit, when Luke, Ben, and Han are discussing what happened to Alderaan, add Luke's line, "It looks like sand people did this, all right. Look, there's gaffi sticks, bantha tracks. It's just… I've never heard of them hitting anything this big before."