Phil Nelson, the stuntman responsible for selecting actors for the film, previously served in the reconnaissance unit of the US Marine Corps.
According to Ridley Scott, Sam Rockwell was originally scheduled to star in the film and had rehearsals, but he was later ill and injured during the rehearsal, so he had to be replaced by someone else.
In the bar, there are two girls named Selma and Louise, alluding to the movie "The End of the Road" directed by Ridley Scott in 1991.
The male actors in the film are required to undergo a series of physical training and tests, including sprinting, long-distance running, 400-yard swimming, 30-yard diving, hundreds of sit-ups, push-ups and squatting jumps
.
The producers filmed two endings. In the other endings, O'Neill died in order to rescue the commander
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