Roy Holder plays a cameo part as the older road worker who talks to Williams when he opens flat window. Holder was a main character in the movie Die größten Gauner weit und breit (1970), by Joe Orton, Williams' close friend.
The music that scores the closing scenes and voiceover and goes into the end credits is taken from the soundtrack for The Hours - Von Ewigkeit zu Ewigkeit (2002), composed by Philip Glass. The first track, during the final diary entry, is "For Your Own Benefit", followed by "Why Does Someone Have to Die?" when Lou tries to wake him up.
The film only briefly hints at the acerbic relationship between Ken and his father, Charlie. In reality Ken had a deep dislike of his father from childhood, considering him a bully and failing to understand Ken's personality. As Ken started to become a success he was annoyed at how his father would try to rattle him, undermine him and how he treated his mother, Lou. They had several rows, one involving Charlie allegedly helping himself to Lou's savings. When Charlie inadvertently poisoned himself, Ken was even briefly detained by the Police who were wondering how the poison got into a cough mixture bottle. This incident even meant that Williams was once denied entry into the U.S. at one stage.
Alan Simpson stated in 1998, that Williams' role in Hancock was not slimmed down by the suggestion or demand of Hancock at all. The "grotesque" (as Simpson described Williams) was a character that he and fellow Hancock writer Ray Galton wanted to get away from to take the show in a new direction with Hancock and Sid James in a sort of double act.