Interview Questions and Answers: Damage control with interview questions
The hard way of finding out that you didn't listen to the interview question is when you're reminded by the interviewer. The remedy is to apologize, and say that you've realized that you phrased your interview answer incorrectly, and give a very good response with your second chance. It's a lot better than the alternative, even if it's hard to feel comfortable giving the revised interview answer.
Losing Track of Your Interview Answer
Interviewees do get sidetracked in the middle of giving interview answers, either by themselves or supplementary questions. To avoid completely destroying your interview answer, double check with the interviewers.
Say 'I want to make sure I'm answering everything here, and I think we've gone a bit off topic, so I need to get back on track. Where had we got to, with the original question, so I'm not repeating myself?' This is a tactful way out, and it also excuses any lapse of concentration on your part, because you're trying to organize your answers. Most interviewers will understand.
Not Fully Answering the Interview Question
This can be a real worry, in the midst of an interview. It happens regularly, and people never seem to quite know what to do about it. The interview answer has either already been given, or you've left something out, and will have to backtrack.
This always happens in the middle of your interview answer, when you've realized while speaking that you've missed something critical. There's only one way out. It's gruesome honesty, and the right interview answer.
'Oh, I left out ...! I'm really sorry, I'll have to rephrase this, to give a correct response. What I should have said was....'
If nothing else this interview answer will convince the interviewers you're trying to do things properly, and the alternative is total failure.
Giving an Incorrect Interview Answer, and Realizing While Answering
It's also quite common to get things entirely wrong, and have to try to repair the train wreck while going off the rails. The need here is for a plausible interview answer, as well as damage control. The fact that you've realized your mistake is actually a positive, (some people don't) but you do have to come up with something to defuse the mistake.
'I've just realized I said something which I didn't mean to say. I said... I meant to say...'