Can a nicu baby accidentally overdosed on opioid (800x prescribed dosed) by nurse develop weakened bones several months later causing fractures?

Hard to know: It is hard to comment on side effects of some accidental dose since the issue has never been studied. However, my impression is that once the kid gets past the initial complications (like not breathing) of the opioid exposure they would return to baseline health. Fragile bones months or years later would bring a defect in bone metabolism (brittle bone disease) forward as more probable.