Visible crew/equipment: Look over Val's right shoulder as Rhonda is supposedly driving upside down with her legs sticking out the back window of the truck cab and you can see a man driving for her. (00:42:40)
Visible crew/equipment: Towards the end, just after Kevin Bacon says "this one's not falling for it," watch for a boom mike right at the top of the screen.
Visible crew/equipment: As the camera pans up to the roof of Bert's house, a film crew member is reflected in the window.
Chosen answer: The machine is a vibrating case cleaner, which is used to polish the brass casings of pistol and rifle ammo. The "dirt" is actually an abrasive polishing compound.
BGraz