Towards the end of the movie Big Daddy gets shot many times in
the body inflicting large bullet holes, including his upper right chest area. At the end, when he turns to look at Riley and the others, the bullet holes are not there.
After Riley lowers the drawbridge, a zombie comes out of the same control room.
The main zombie antagonist, who is seen throughout the movie, carries an AUG assault rifle and fires it repeatedly. However, he cumulatively fires more than the clip can hold and is never seen reloading.
Towards the end of the film when Big Daddy pours the gas in Kaufman's car, the gas pump is never cut on and is visible with the lever 'off' in all shots.
In the scene when the stenches break down the wire mesh gate (about 37 minutes in), a guard in the tower throws a rope and slides down (to be eaten by stenches), even though a perfectly good ladder can be seen on the tower.
When one of the military men attempts to throw a bomb his hand is cut off by a zombie. He falls to the ground, covering the bomb he was holding and gets blown up. When his body lands, his other hand falls off, revealing that it's a mannequin hand.
At the start, when the Skyflowers stop and they are leaving the supermarket, 3 zombies are shot by the guy in the truck. The third zombie falls before being shot.
When Riley makes a run for "Dead Reckoning" after lowering the
drawbridge, he is clearly aiming far left of the first zombie he "shoots".