When Don or Paul is supposed to be driving the truck on the interstate, it is the director. The truck was challenging to drive (stick shift)
The spine of the jewel case for Don Bradleys CD is a different name and color than that of the cover.
The art dealer asks to buy three paintings but only names 2 of them. The script was changed before this shot because Benjamin (the writer/director and artist) didn't want to sell one of the paintings.