Continuity mistake: When Beer Guy gets his eye ripped out, he bleeds on the blonde girl. When we next see her, prodding the dead body on the billiards table, the blood pattern on her face is very different.
Continuity mistake: When Beer-Guy gets vomited on by the creature, there are no maggots or bugs on him, only green goo. Yet, seconds later, when he is washing himself off, there are maggots all over his hair and face.
Continuity mistake: When Tuffy's son is killed, you see his shoe fly by the camera, with his severed foot still inside. Shortly after, when you see the shoe again, it is empty, and simply covered in blood.