Somehow being able to hold and shoot accurately a gun on full auto that should dislocate your arms. (See: Death Machine)
Also, not really a cliché but more of a common trait, the part about everyone except 1 or 2 people in the squad/army/invasion force being a bunch of redshirts that can hardly hold a name. You know, those unlucky bastards that always get shot first, step on the mines, get hit by horrible collateral damage from explosions etc. etc.