Russ Tamblyn's mother hated the film and blamed it for ruining her son's film career.
John 'Bud' Cardos also coordinated all the fight sequences.
Director Al Adamson instigated the project after a more expensive production that he'd been working on collapsed. He was able to put the financing together with producer Samuel M. Sherman, hoping to cash in on the wave of biker movies that were enjoying popularity in the late '60s.
Generally thought to be the first film to feature someone being killed by having their head shoved down a toilet.
Shot in a mere 8 days.
Shot on the more inexpensive 16mm stock (to compensate for having to pay "named" actors) and later blown up to 35mm for theatrical release.
The film put Independent-International Pictures on the map. It was the company's first production and proved to be a big hit at the drive-ins in 1969.
The film was shot at the Spahn Movie Ranch in Simi Valley, CA, at the same time that Charles Manson and his "family" was living there. In fact, this was exploited in the film's advertising with the line "Filmed in the exact location that the Tate hippie killers lived their wild experiences!"
The red tinted sunglasses that Russ Tamblyn wears in the film were his own idea, and his floppy hat was a carryover from his previous film, Scream Free!.