When questioning his father in the morgue Jack refers to "the remaining four nukes". There were originally five nukes; Jack witnessed one detonate in Day 6: 9:00 a.m.-10:00 a.m. (2007), and disarmed another himself in Day 6: 1:00 p.m.-2:00 p.m. (2007). He should therefore have known that there were three remaining nukes, not four.