Here is how I would have REWRITTEN this movie

Let's pretend I'm given this script and asked to fix it to make it work. Here's what I would have done.

1) The government is bad. Why not make them in cahoots with the Aliens? An agreement with the aliens that they can come here and hunt, and kill, and take human samples, in exchange for military technology.

2) McKenna and his army team were set up as sport in the jungle. The "best of the best" sent to more or less be sport.

3) McKenna survives the hunt. He takes the technology, sends it to his kid, and escapes.

4) McKenna took something he wasn't entitled to. Now both the government and the Aliens are after him to take it back.

5) Back in the States, he is arrested, and instead of being on a bus, he's in an underground cell with the other loonies. The first fight to escape takes place under ground.

6) The land escape begins. Imagine a scene of them in a bus being chased by a predator and shooting at it (Jurassic Park homage.) Some get killed, some get injured.

7) McKenna swings by and picks up his son.

8) McKenna retreats to the forrest with his team and a planning session begins. This is the training scene missing in this movie.

9) When ready, the boy activates the weapons, which lets the predators and military know their whereabouts. "Come and get it." He tells them.

10) They come. The major team fight scene of the movie. Aliens and their human protectors are killed left right and center.

11) The boy is taken. This sets up the rescue mission.

12) Boy is taken to Amazon Jungle and dumped. Government tells McKenna that he has to go rescue his son. If he doesn't, they will drop a big bomb, a scorched earth weapon. McKenna goes.

13) McKenna fights the Predator alone in the jungle.

14) McKenna prevails and rescues son.

The End.