There is a key sequence in which a dialogue scene happens in an apartment which overlooks ground zero.

BBC: 25th Hour

The key sequence in the finale is too brief and not interactive enough.

CNN: Review - Wild Wild West: The Steel Assassin

Another key difference to the current sequence is that the two props have to touch their opposition number's shoulder.

BBC: New scrummaging law takes force

This would change when the virus crossed paths with cells containing a very specific DNA sequence, a sequence that would act as a molecular key to unlock secondary functions that were not so benign.

FORBES: Hacking the President's DNA: When Synthetic Biology Meets National Security

But since the first draft sequence of the human genome was released in 2000, scientists have realized that junk DNA plays a key role in switching genes on and off.

FORBES: Magazine Article