When James Caan walks by a paperback spinner rack, a paperback title "Ruined Virgin" can be seen. It appears that this is not a real book. This book has only been seen in the movie La ragazza yè yè (1966) with Ann Margaret. There is a scene where Ann Margaret dances with the book in hand and you can see the cover. Margaret also reads the cover aloud. It appears that the book was a prop in the movie from 1966 and later reused for Slither in 1973.
Peter Boyle does an imitation, singing, and James Caan gets it quickly, saying "Mr B." which referred to Billy Eckstine, the song "Everything I Have Is Yours".
The van is a 1973 Rec Trans Discover 25 R. It was based on a Dodge platform. The body was all fiberglass and the vehicle weighed five tons and got 10 miles per gallon.
The ominous black vans following James Caan have their own formidable-sounding score. The main score is upbeat and jazzy until the vans are shown, at which point the sinister groove kicks in: but only when the vans are visible on screen.