According to Lynn Lowry, the shoulder that Nurse Forsythe stabs with the fork is actually that of David Cronenberg. A pad was inserted under Cronenberg's shirt for Lowry to stab, but, unfortunately, she missed and hit Cronenberg's real shoulder instead.
Canadian journalist Robert Fulford attacked the content of "Shivers" in the pages of the national magazine "Saturday Night." Since Cronenberg's film was partially financed by the taxpayer-funded National Film Board of Canada (or NFB), Fulford headlined the article "You Should Know How Bad this Movie Is: You Paid for It." Not only did this high-profile attack make it more difficult for Cronenberg to obtain funding for his subsequent movies, Cronenberg later said that Fulford's attack also resulted in him being kicked out of his Toronto apartment.
Susan Petrie was unable to cry, so David Cronenberg used onions to help her produce tears. This worked, but the camera was out of focus when the scene was shot, and because Cronenberg was out of onions, Petrie gave her consent to let him to slap her on the face. He did so until her face was numb from all the takes. He finally settled for a series of takes he found to be less than satisfactory.
The trivia item below may give away important plot points.
An audio commentary of the film with members of the crew and critics mentions towards the ending of the film, when the 'infected' jump into to pool many of the crew behind the camera took off their clothes and jumped in as well unnoticed and remained in the final cut of the film.