The Munro portrayed in the film recalls the death of a twin brother named Ernie, who died when a tree fell on him. The real Munro had an older brother who was killed when a tree fell on him. Munro also had a stillborn twin sister. The real Munro had set numerous speed records in New Zealand during the late 1930s through the early 1970s. However, these records are only implied in the film. Munro was never known to actually urinate on his lemon tree; film director Roger Donaldson added that detail as a tribute to his own father, who did.