: Military operations often begin during this window to utilize the cover of darkness and the element of surprise. Significance to the Film

: While often used broadly for any "ungodly hour," filmmaker Kathryn Bigelow noted that for the film, it specifically refers to 12:30 a.m. . This was the time Navy SEALs launched the actual raid on the Abbottabad compound.

: The term is a play on the 24-hour military clock. "Zero" refers to the hours before 10 a.m. (starting with 0), "Dark" denotes the nighttime or pre-dawn hours, and "Thirty" indicates 30 minutes past the hour.