The character of Buzzy was originally written as a man. When Hilary Swank read the script, it was the character that "spoke to" her the most, and she asked writer/director Greg Marcks to rewrite the role as a woman so that she could play it, and he agreed.
When Mark throws the jelly donut at the car Frank is driving, we see it hit the windshield on the driver's side. When the camera angle changes to an inside view, the donut splatter is in the center of the windshield, and when Frank switches on the wipers the majority of the splatter is picked up by the right wiper. After another cut to an outside view, the splatter is back to being mainly smeared around the left wiper.
When Frank drops the book and shirt on fire in the sewer and gets the dog into the car, the flashlight is on the sidewalk. When he hops in the car, the flashlight is gone.