Goofs

Kelly runs outside and jumps into a blue truck. When she realizes the keys aren't in the ignition, she gets out and slams the trucks door shut. In the next shot the door is suddenly wide open.

When zombie Danny kills Chloe, the office door is open. When Kelly leaves the office after the outbreak however, the door is now closed.

When Patrick looks over the bathroom stall he's been hiding in, a zombie is staring at himself in the mirror. The mirror is fogged up as if the zombie was breathing on it. Zombies cannot breathe - they are dead.

When Kelly escapes from the zombies into the camera runs, the sound of the door closing can be heard before Kelly actually closes the door.