1. What - from all the things you have accomplished while working here so far - are you most proud of?
2. What did they do for the last social outing?
(Look for their face reaction as they answer the two questions. If they look surprised, or don't have a good answer, you may want to look elsewhere.)
And, if not already covered in the interview (which they really should):
- How technical is the CTO? Can/does s/he program? Ph.D. Degree?
- Who (name and function) does the group (my boss' boss) report to?
- What does the company do for training its people? Is there an annual budget?
- What is the attrition rate in the team?
- What is the career path anticipated for the role under discussion?