Continuity mistake: When the predator finds Edwin you can see a plasma caster on its right shoulder. When Edwin explodes and the camera is filming behind the predator there isn't a plasma caster there any more. (01:30:06)
Continuity mistake: When Royce kills the Predator at the end, he slices the head off, and it falls backwards, and the body falls forwards. One of the next shots now shows the head to now be in front of the Predator body.
Continuity mistake: When Royce is running around the last Predator hitting him with an axe, the plasma caster on the Predator's shoulder changes from left to right between shots.
Continuity mistake: When Isabelle shows Royce the planet's weird magnetism by using a leaf in some water, she puts the leaf on the water and it is very flat. But after the cut and close-up of the leaf it is very curled up and cup like. It is very obvious that it is not the same leaf.
Continuity mistake: After Royce decapitates the predator his head falls on his back, but seconds later the head is on his front.
Continuity mistake: After the predator with the jaw on his helmet explodes the ship, the cannon on his shoulder changes from the right to the left.
Continuity mistake: While Edwin holds the pics of the two boys asking for Royce's help, he grabs the pic differently between shots.
Continuity mistake: While Royce is helping Isabelle from the spike hole, besides Isabelle there is a rock that changes to some leaves.
Continuity mistake: When Royce uses the leaves as a compass, the leaves change shape from curve to flat and even the spinning changes direction.
Continuity mistake: At the beginning Royce is pointing his gun at Nikolai's cheek and ear, but in the next shot the gun is pointing in the air.
Chosen answer: Indeed, it's an interesting question, and not one to which any answer is given. In the absence of any other information, your speculation that the predators have taken various plant species from other worlds to study and just make their hunting environment more interesting is as good an explanation as any other.
Tailkinker ★