 Director Tony Martin (III) (qv) had a rule that everyone who  worked on the movie had to be seen on screen. One of his boom  operators refused, but Martin got lucky when the reflection of that  particular boom operator is seen in the security guards window  during the Northey/XL9000 scenes. Martin decided not to use optical  effects to remove the boom operator so that his rule was obeyed by  everyone. Martin reveals this in the DVD commentary