According to the interview with Paige Conner on the Code Red DVD, Shelley Winters smacked her for real several times while both rehearsing and filming a key confrontation scene.
Paige Connor wore a bald cap for her scene in the greenhouse. All of the other kids in the greenhouse scenes had their heads shaved.
Paige Conner had trouble saying harsh profanity to Glenn Ford in her big confrontation scene with him.
Sam Peckinpah had trouble remembering his lines. Because of his difficulty with the dialogue, his voice was dubbed by another actor.
According to Lance Henriksen, the cast agreed to do the movie to get a free trip to Italy. Henriksen dislikes the movie, calling it "a real turkey."