The protagonist in this movie carries a Heckler&Koch MP5. In at least two scenes (after approximately 52 minutes) the director inserted random close-ups of a AR15-type weapon being shot. Not only do these two rifles look nothing alike, even the backdrop is radically different (the actual scene is set in a back alley, the close-up footage in a forest).
When Dacascos parks his car right outside the dead-guy's grocery store, the car faces towards the entrance door. When he leaves the store and gets in the car, the car now faces the direction where he wants to go.
Throughout the course of the film, the bombs set around the city count down from 48 hours until the city is destroyed, but during the last 10 or so minutes of the film, one shot of the bomb timer shows 40 seconds and clearly counts up to 43 seconds before cutting away. The timer then continues counting down.
Renchard is reading a book and his eyes start closing because he is sleepy. We can see at the left page an image of the statue of Hercules. When he wakes up you can still see the image, but when he puts the book down the image is not there and now on the left page there are letters.
There is a scene where Renchard is running out of an old garage that he's been in before after being spooked. As he leaves, he hits one of a set of double doors and it opens and closes behind him. Clearly the garage doors are both closed. He hops in his car and turns to face the door, gun ready in case anything comes out. Both doors are now as wide open as they can be and in fact are clearly propped open with sticks.
In the seventh minute his nightstand alarm clock comes on with a radio broadcast, while flashing different times. He then picks it up (it is clearly not plugged in) and throws it to the floor, where after a few seconds it comes on again.
In the fifth minute after the fight, Renchard ignites a flare to burn the bodies. A flare would not incinerate bodies without an accelerant.
In the ninth minute he opens his medicine cabinet and a pill bottle is on its side with the top facing the camera. The top of the bottle reads 'push down & turn.' There is an arrow pointing to the left, accompanied by 'open.' This is counter clockwise, contrary to medicine bottles which open clockwise.
In the 16th minute when he throws/kicks the gasoline container into the trunk of his car. by its flight one can tell that it is empty. Also, there is nozzle attached, meaning when he threw it in (rather than pace it upright and remove the nozzle), gasoline would have spilled.
When one sees the corpse of Paul in the 16th minute, his right hand is bare bones posed on the outside of his hand (thumb-up). Once skin and ligament rot, the finger bones would have collapsed, having nothing to hold them together.
Some of the zombies have no make up on their legs, so when you get to see their bare legs they look completely normal even though their entire upper bodies have rotted.
In the ninth minute he takes out a plastic container of coffee which is clearly the Folgers brand, with a black marker drawn down over the letter 'l.'
In the third minute Renchard gets out of bed when the house's alarms go off. He is wearing boxer shorts and shoes in bed.
As with other post-apocalyptic movies (Book of Eli, for example), it seems odd in a post apocalyptic world (of a movie released in 2007), that his vehicle would be an operating 1970s model.
In the 45th minute there no zombies around, except for two crawling - inexplicably crawling along the roof of the white van, toward the front.
In the 77th minute when they enter the tunnel, they are driving on the left hand side of the road, on the opposite side are lane markings indicating that a right hand turn can be made from the inside lane. Based in the US, this makes no sense.
During the initial fight scene with the zombie/vampires, Renchard is about to set a creature on fire that's hanging upside down, there is a VERY noticeable shadow on the ground, like another creature is coming after him, but no one appears. It had to have been a crew member walking in front of the spotlight.
In the 44th minute a zombie comes out of the dry ground. This is a completely new and unexplained scenario in a zombie movie.