While the National Guardsmen give Travis good advice about shooting the .50 caliber rifle (hold it tight to the shoulder, press, don't pull, the trigger, etc.), they failed to warn him not to put his eye against the scope. If he had fired with his eye in contact with the scope, the recoil would have slammed it into his eyebrow, bruising or even splitting it open.
The term "cobalt" is the army's terminology for the humane extermination of the infected and wounded - people who will not be able to survive the apocalypse.
This is the first episode of the series to have a higher viewership than the previous episode.
First appearance of Victor Strand
When the series was first under development, it went by the working title of "Cobalt".