The misleading title refers to a nightmare one of the child characters in the movie had and it's just a generic term he comes up with to call the imaginary monster from his dream that he fears. The movie uses his story as a very loose metaphor for its plot.
Dr. Rachel Carson is a reference to American marine biologist ad conservationist Rachel Carson, whose writings, including the book Silent Spring, are credited with advancing the global environmental movement.
Steve Railsback has stated that he is embarrassed by his involvement with this movie.
The movie's original title was Green Monkey, but it was changed at the last minute to avoid confusion, since there was a popular conspiracy theory at the time that green monkeys had spread AIDS to humans.
Known in the United Kingdom as Invasion of the body suckers in the days of VHS.