Mute Witness

Writer- Producer-Director Anthony Waller met Sir Alec Guinness quite by chance in Hamburg in 1985, where he asked him if he was interested in doing a one-scene cameo. To his surprise, Guinness said he'd be delighted and that he would do it for free. The problem was that Guinness was fully booked for the next eighteen months, so Waller suggested they shoot the scene the following morning in an underground car park. Guinness readily agreed and, true to his word, took no payment with the provision that he not be credited in the film or there be no publicity surrounding his involvement in it. This is why he is billed as "Mystery Guest Star" in the end credits.

When Karen is holding the gun inside Billy's apartment, it suddenly disappears from her hand. A few moments later, it appears in Andy's hand.

For his cameo appearance as The Reaper, Alec Guinness is credited as "Mystery Guest Star".