Mitchell needed his eyeball re-attached in hospital and the Breakers initially feared his career was over.
"I don't think so," said Henare. "Once we found out he was going to be okay, everyone was pretty happy.
"I don't know what's happened in the last two weeks. Maybe I've done a s**t job holding each other accountable to our standards.
"When things get tough, there's a bit of angst and worry on the faces out there, instead of trusting each other and trusting the process.
"I don't know if we can put that one behind us. There's an underlying 'quit' in us right now when things get tough.
"I saw a lot of quit out there and that's concerning. If we perform like that against Adelaide next week, we'll lose by 50."
Breakers captain Mika Vukona echoed Henare's sentiments.
"To come out and play like that in a must-win game is pretty disgusting," Vukona said.
The Kings accounted for Brisbane on Friday night and remain in the hunt for a finals berth.
"Our playoffs started two weeks ago, and this weekend was do or die," coach Andrew Gaze said.
"There was no finals if we'd dropped these two, but we have to do it again next week and the week after."