Visible crew/equipment: When Ford runs past the caravan to chase the Vogons with a towel, you can see the cameraman, and about 4 other crew members reflecting in the caravan's surface.
Visible crew/equipment: On the DVD version, in the scene where Slartibartfast is taking Arthur to his home with the "air lift", when over the fields of England, on the bottom left corner you can see the shadow of the helicopter with which the aerial footage was shot. (01:27:55)
Chosen answer: Because it was a radio show originally, Douglas Adams would write broadcasts from show to show. He did not know where something would lead, which let the plot become random and funny. So ultimately it was originally created to be funny, then he found a way to link it back in later.