I also noticed the grammatical mistake on MU/TH/UR's screen after interrogation: it should have been 'Ensure', not 'Insure'!

"Ensure" and "insure" are both valid words/spellings for this. The use of "insure" is far less common, for this meaning, though. Both include "to make (something) sure, certain, or safe" in their definitions:

http://www.merriam-webster.com/dictionary/ensure

http://www.merriam-webster.com/dictionary/insure