For instance, we are told that the sun doesn't move in the sky, yet the planet clearly has a day/night cycle. And why is it when they reach the edge of the forest and see the planets and moons in the sky, they don't see this earlier when they reach the clearing where the test the planet's magnetic field?
The opening sequence where we are introduced to the characters is weak - too much too soon and we don't get to find out much about them. They are simply archetypes. Also, there is absolutely no character development. Additionally, the doctor fails because there are no hints he is the murderer - it just gets revealed towards the end. There should have been hints to foreshadow.
The Predators are really weak villains. Sorry. Yes, they look amazing and have a great concept, but other than that there is absolutely no character. They are essentially the ultimate hunters. I would have liked to see some characterisation or learn more about their culture. Oh, and they seriously underused the falcon predator.
Lawrence Fishburne's character was too weird, and was just a plot device.
What's with the patronising treatment of Asians? Why is it that a Japanese character has to be an expert with Samurai swords? There was nothing at the start to indicate that, and he was pretty boring - the silent Yakuza. Further, I hated what they did to the female character - she became the helpless female to be rescued by the hero at the end. I hate bringing female empowerment into my critique, and I acknowledge what role she played at the end, yet she was still largely powerless and designed to make us dislike the doctor.
Having said all that, I still enjoyed the movie.

3 stars.