Things may have changed since I was there but just in case they haven't:
Ask about high turnover rates (not how many people they're hiring because of "growth").
Ask how long the last 3 people stayed at the company in your specific role. Ask why they left.
Ask if people's roles/titles/responsibilities can/do change within the first 10-60 days of hire or every few weeks in general.
Ask how many people left or were suddenly dismissed within 90 days of hire.
Ask how often teams shift around between managers and projects.
Ask how many people are related to or close friends of the executive suite. Ask if you'll be working with any of them directly.
Ask what the company direction is for their products. Note any short term tunnel vision, side stepping or generalities.
Ask what the end of year bonus is specifically based on as it relates to your role or performance. Again, note any generalities or side stepping.