With regard to the "WTF..." issue, I would recommend that you hold a post-mortem. Get together the relevant stake holders (head of sales, head of development) and review 1. What Happened, 2. What was the root cause and 3. Remediating Actions.
If its treated as an opportunity for improvement, and specifically not an exercise in assigning blame, then I've seen it be very successful. People have knowledge gaps, incorrect assumptions, institutional knowledge from other institutions, or just flat out make the wrong call under pressure, in hindsight. Learn from it and improve. That said, I've also seen it be completely pointless when a team believes it to be an exercise in blame assignment, no matter how much its been promised to the contrary. If its not possible to hold such an exercise, then the company has way bigger problems, and wouldn't you much rather work somewhere healthy?
If its treated as an opportunity for improvement, and specifically not an exercise in assigning blame, then I've seen it be very successful. People have knowledge gaps, incorrect assumptions, institutional knowledge from other institutions, or just flat out make the wrong call under pressure, in hindsight. Learn from it and improve. That said, I've also seen it be completely pointless when a team believes it to be an exercise in blame assignment, no matter how much its been promised to the contrary. If its not possible to hold such an exercise, then the company has way bigger problems, and wouldn't you much rather work somewhere healthy?