Visible crew/equipment: When Zaphod says his first line "I certainly didn't survive.", you can see the person who plays his third arm standing behind him.
Continuity mistake: When Ralph lifts Bill's car the first time, the blue license plate on the front bumper is gone, but when Ralph is amazed at the suit's power he lifts the car a second time, and the blue license plate is in its proper place on the bumper. (00:35:50)