1. The interviewer springs a surprise group interview. Many companies prefer candidates to be screened by multiple people, if only to make the process efficient (Efficient, but not necessarily effective). Then you get to sit on one side of the table while three or four or even twelve people sit on the other side, and big fun is had by all. Or not.
What to do: You can't change the hiring process, but you can prepare. Ask questions when you're contacted to schedule: How the process works, who you will speak with, and especially whether a group interview is involved.
If you'll meet with the group, mentally prepare. Be ready to spread your attention to everyone in the room – especially the quiet people. Don't worry about pausing before answering questions. In a group setting it's less noticeable when you take a second to gather your thoughts. Above all, remember in a group setting it's easy to fall into "presentation mode." Don't. An interview is a conversation and a group interview is still one conversation... just with more people.
2. The interviewer talks about possibilities. Many interviewers sell the position, the company, or even themselves. They talk about potential projects, potential expansion, potential opportunities if you're hired... but they make those possibilities sound definite and absolute, possibly causing you to accept the job based on unrealistic expectations.
What to do: Listen closely to any discussions regarding the future. Ask for details. You don't need to interrogate the interviewer, though. Be subtle. Don't say, "Is that project actually approved and funded?" Ask a leading question like, "That sounds great; I bet the approval process was intense."
Most importantly, use what you know about a job -- current duties, reporting chain, salary, benefits, etc -- to decide whether or not to accept the job. Then possibilities that turn out to be realities are a bonus.
3. The interviewer sticks too closely to a script. Providing a concise answer to an interview question is great, especially when a question is specific. But an interviewer who does not ask additional questions can fail to get the full story of your skills and achievements.
What to do: Be alert for the "I'm just checking off the boxes" interviewer. If your first few answers fail to spark additional conversation, start expanding. Sell yourself a little more. Share details about why you took certain actions, how you had to adjust, how things turned out... assume each of your answers should be more like a brief story than courtroom testimony.
If the interviewer doesn't ask, find ways to tell. Come prepared with a few talking points that highlight your skills and experience and find ways to weave them in.
4. The interviewer monopolizes the conversation. Monologue interviewers are a major challenge. Interrupt too often or try to regain a portion of the conversational balance and you seem rude; sit passively and the interview is a waste of time.
What to do: Seize opportunities to interject by responding. Say an interviewer drones on about the challenges -- challenges he always overcomes, of course -- of running a multi-facility, high-profile expansion project.
Try to shoehorn in a, "Wow, that sounds really hard... I know when I was in charge of a team that redesigned our network platform the most gratifying thing was getting everyone to pull together. You may not accomplish much but you will manage to share at least one achievement -- and maybe plant a small seed in the interviewer's mind that you're a little bit like him. (Just not nearly as awesome as he is, of course.)
5. The interviewer doesn't get input from others. Smart interviewers find out how you acted and what you did while you were waiting, interacting with other people, etc. "Lobby behavior" often says a lot about a candidate. But many interviewers don't ask for other opinions.
What to do: Be at your best throughout all stages of the process. On the phone, by email, when talking to the administrative assistant who schedules the interview, while waiting in the lobby... make a great impression on everyone. That way, even if the interviewer doesn't ask other people for input, some may still volunteer.