User blog comment:Bob the Wikipedian/The cliffhangers!/@comment-185.15.0.6-20130525201802/@comment-6905051-20130528070838

That definitely can be counted as bloopers by the writers. I guess in their hurry to zombify Nick they forgot he should have precautions. Or maybe they wanted to show that Nick's characteristic head strong behaviour and him rushing towards scene of crime since its kind of an emergency.