Taking the fall for a situation, in order to protect a coworker, is a less than ideal situation. Whether committed through a misguided sense of teamwork or an inability to communicate the facts, it rarely reflects well. It can compromise the integrity of the team and hamper the growth opportunity of the person at fault. It is likely guarantees that the person who made the mistake will repeat it. It attests to your inability to communicate effectively and presents the likelihood that you are easily taken advantage of. Talk to the interviewer about your thoughts on taking the fall for something you did not do. If this situation has happened to you, explain what you learned from it, and how you've applied those lessons, moving forward.