(at around 17 mins) When the army is examining the barrels of corpses, two personnel are in full anti-contamination suits complete with masks & breathing apparatus. Less than 3 feet away are various soldiers, sans protection, who don't seem concerned.
When the barrels of dead bodies fall from the military trucks two barrels are scene falling, land, and stop in the middle of the street/bridge. In the next scene one barrel roles hast-fully off the cliff into the creek.
When Jesse Lucy and Tom are talking about going to look around town you can see Doc Mandel in the background examining Joey and Ed still wearing his red sweater. After the others leave and the shot returns to Doc his sweater is gone has been replaced by a white lab coat.
The Zombie shot in half had lost his hand in the car window in the previous scene. When he lifts his torso by his hands to attack the gang in the hospital cellar, his hand reappears for one shot. In the commentary, however, the director mentions that this actor was one of several used for multiple scenes. His description suggests that this wasn't supposed to be the same zombie from earlier.