I would have said something no matter how deep into the interview we were but I tend to be a bit blunt at times, even in an interview. And I'm pretty sure I talked myself out of at least 2 positions over the years, but that's how things go.
I had the opposite happen once; had a headhunter send me to what was supposed to be a DBA interview on mainframe equipment. Turns out it was a cattle-call and there were at least 10 people in the waiting area with me, and I noticed that they'd call someone in, interview them, and they'd leave. I was unemployed at the time so I pretty much had all day, but once I noticed that the room had turned over everyone that was there before me and was starting to call in the people who came in after me, I asked the admin/receptionist what was going on. Soon after that I got called in and someone on the interview team apologized and told me that they were looking only for Oracle DBA's, and they weren't sure why I was sent there but they would forward my resume to the appropriate area and I might get a call from them. Never did get that call, and that headhunter stopped calling me for some reason...
I had the opposite happen once; had a headhunter send me to what was supposed to be a DBA interview on mainframe equipment. Turns out it was a cattle-call and there were at least 10 people in the waiting area with me, and I noticed that they'd call someone in, interview them, and they'd leave. I was unemployed at the time so I pretty much had all day, but once I noticed that the room had turned over everyone that was there before me and was starting to call in the people who came in after me, I asked the admin/receptionist what was going on. Soon after that I got called in and someone on the interview team apologized and told me that they were looking only for Oracle DBA's, and they weren't sure why I was sent there but they would forward my resume to the appropriate area and I might get a call from them. Never did get that call, and that headhunter stopped calling me for some reason...