Corrected entry: In any scene with Billy Zane, his character is shown with a fancy sniper rifle. This sniper rifle is supposed to be a Heckler & Koch PSG-1 (about $10,000). Obviously the director didn't want to be banging one of those around in the jungle as in the movie Billy Zane's "PSG-1" has a front ghost-ring sight in addition to the scope. A real PSG-1 does not have a front sight at all as the scope (a fixed 6x Hensoldt) is affixed to the rifle before it leaves the factory. The H&K MSG-90 is the military version of the PSG-1, it has a ghost ring site, however it does not have the expensive pistol-grip/buttstock that the PSG-1 is famous for. Hence to save cost they mocked up a MSG-90 (about $3,000) to look like a PSG-1 (about $10,000).
Corrected entry: When Tom Berenger's character is in his ghillie suit in the open field and guards are patrolling with dogs there is no way that his scent is going to be disguised by snuggling up to a pile of manure, especially after his and Zane's characters have been getting ripe from days of operating in the bush.