Filming took place in-and-around various locations in Toronto, Ontario. The Kincaid estate was Valley Halla Estate by the Rouge River, and the opening sequence was filmed at Scarborough Bluffs Park. The animatronics used to realize the snake were designed by Mendez and Neal Martz. Originally six different snakes—each performing its own function—were to be built, but with a limited amount of money and time constraints, this idea was scrapped and doing as much as possible with a single mechanical snake was considered more feasible. While filming commenced in Canada, Mendez and his small crew of six built their robot monster in New York in autonomy over the course of eight weeks between August and October 1981. Two 22 ft bodies, three 6 ft necks to accommodate an armature, and puppet heads were used to bring creatures to life. The gore effects, including the graphic results of the snake's bite, were designed and realized by Academy Award-winning makeup artists Dick Smith and Stephan Dupuis, and featured heavily the former's signature air bladder technique. Invited to watch the filming in Toronto, both Maryk and Monahan left after three days upon becoming irritated with the constant alterations being made to their work.