Don’t hide behind the “we” when you know you are the “I” who is clearly responsible. That is not team spirit, it is cowardice. Declare boldly that “I am responsible for what went wrong”. Just using “we” doesn’t make a team. However, genuine “we”s are an indication of already existing team-spirit. As an example:

Case – 1:

Team Member A: “My bad. I should have unit tested my code. I could have prevented the escalation and bad reviews.”

Team Member B: “That’s ok. It happens. Even we are responsible. We should have reviewed your code more diligently.”

Case – 2:

Team Member A: Had we reviewed the code diligently we could have prevented this disaster.

Other Members: Surprised to see how smartly A escaped blame.

Which one of the above is a true team? I suppose it is pretty clear – the one with the right balance of I and We.