What factors may have been present that caused the error in these above examples?

A 28-year-old male with Burkitt’s lymphoma was receiving methotrexate via a spinal route. The doctor documented that “vincristine and methotrexate [were] given intrathecally as requested”. The warning label on the vincristine was incomplete, in small print and read in a darkened room. The error was not recognized until five days later, after paralysis of the lower limbs had occurred. The patient died after
28 days.

Questions
1.What factors may have been present that caused the error in these above examples?
2.What steps could the organization take to ensure that the catastrophic events are not repeated?
3. If you were the hospital manager what would you do in each of these cases?