Location filming at the Melbourne Zoo, which took place in September 1971, didn't quite go according to plan. One scene required a gunman to throw his rifle into the lion enclosure. All went well until two lion cubs pounced on the rifle and started playing with it, then the cub's father came along and smashed the rifle with very little effort. The incidents amused all of the cast and crew, except for the producer.
Two of Sen. Det. Jim Patterson's children, Jimmy and Sally, were played by the real life children of Norman Yemm, Bryden and Jodie Yemm.