Hm, I ask because it's a good way to see what type of learning environment it will be. Maybe pay attention to how the people around you are treated after a mistake is made.
I did make a mistake on a personal note and my boss was very relaxed and fair about that. In general, people don't seem to have any problems helping each other out at all. Now that I think about it, its a great work environment, and the CEO has a very good track record too. Also judging from our funding and customers, we're going to do well! Guess that answers my questions then :p.