Visible crew/equipment: In the scene where Joe goes to Buffalo Bob's house, as he is pulling up to the house you can see the shadow of the camera man in the passenger's seat.
Visible crew/equipment: When Joe is having sex with the girl after she says she is not his sister, there is an outside shot of the shack shaking with a lamp rocking back and forth. If you look carefully, you can see the filament used to make the lamp move.
Answer: It's not so much a joke with a punchline, but more like a funny phrase. He was affiliated with the mob, and as such, has most likely been in violent situations. He asks "does your mother sew" and then punches his refelection in the fire extinguisher case (someone's face if a fight was really happening). The "get her to sew that" comment implies that the person he hit would have needed stitches. (thus the reference to sewing.)
Jazetopher
He was referring to fixing the hole left in the clothes after being shot.