Other mistake: When Trash first comes back to life as a zombie there is a shot of rain falling and smoke swirling. The shot plays forward, then reverses for a second or two before playing forward again. The rain falls up and the smoke reverses direction.
Other mistake: When the zombies are climbing out of their graves, one is seen as a skull that rises, opens its eyes and mouth. If you look closely in its mouth you can see some kind of wire or control used to move the puppet. It is more clearly seen when the footage is reused at the end and the shot freezes for the closing credits on the same shot of the skull.