(at around 33 mins) In the Ultimate Version, when the prisoner came back to fight with the zombies, in one scene, he smashes a guy's head to the tree trunk then the next scene, he suddenly has a gun in his mouth and one in his hand when he knocks the zombie's gun out of its hand.
(at around 42 mins) One of the detectives says (in the subtitled version) that he was trained at FBI HQ at Langley. Langley is the headquarters of the CIA, not the FBI. This fits the character, though, who seems to lie about his abilities throughout the movie.
(at around 42 mins) In the English dubbed version, one of the characters explains that he grew up in Yellowstone Park in Canada. Yellowstone Park is in the United States and since it's a national park, no one could be from or have "grown up" there. This fits the character, though, who seems to lie about his abilities throughout the movie.
In many of the fight sequences, wires are visible on the actors when performing high jump kicks and/or acrobatics
(at around 1h 16 mins) After Prisoner KSC2-303 gets shot in the face, he falls down a hill. "The Girl" then finds him lying dead on the ground. Although he is "dead", you can see him breathing.
The first time the main character encounters zombies in hand to hand combat, a rope harness can be seen pulling the zombie back towards the tree.
(at around 6 mins) When the car arrives to pick the two prisoners up (at the beginning of the film) the camera crew and their equipment are reflected in the car's window when one guy opens the door.