Shot in 1983, but not released until 1986.
The house Professor Bennett lives in is the same house from the Horror movie House - Das Horrorhaus (1985).
Kevin Peter Hall who portrays the Monster would go on to play a much more sophisticated baddie in the sci-fi horror Predator (1987) four years later in 1987. Überfall im Wandschrank (1986) was filmed in 1983.
The six-fingered monster hand from the poster art of this movie were also used in some of the posters and video cassette box art for Watchers - gnadenlos gejagt (1988).