How do call backs work for Amazing Race 19?

In "The Amazing Race 19," callbacks occur when teams that have not completed a leg of the race within the allotted time can potentially rejoin the competition. If a team finishes a leg in last place but is not eliminated, they may receive a chance to return during a designated callback episode, where they must compete in a challenge to earn their spot back in the race. This mechanic adds an element of suspense and strategy, as teams must navigate both the challenges of the race and the possibility of facing eliminated competitors.