Revealing mistake: As Sgt. Highway turns the dead body with a cigar in the pocket you can see its right arm move to avoid twisting. (01:38:05)
Revealing mistake: Near the end they land on the island. After they cross a bridge a soldier shoots an explosive and blows up a machine gun position. Just after that, look at the muzzle of Highway's rifle. It isn't open like it should be but has a type of plug to ensure only blanks can be used.
Answer: It's because it's a movie. The plot could not ably handle the stories of twenty different characters while maintaining the action's pace and a cohesive story line within a two-hour time frame. It instead focuses on a few key characters.
raywest ★