The scene where Cliff drives his Mini motor car under the colonnade of the Birmingham Council House was a stunt, in reality, performed by local motor racing legend and night club owner Martin Hone.
When Cliff goes on board his canal boat, its dimensions on the outside appear to be rather normal, long and thin. However, once inside it's a rather spacious interior.
The name "Brumburger" is a reference to the use of "Brum" as a shorter alternative to Birmingham. This derives from "Brummagem" which was an alternative historical name/spelling to Birmingham.