David Croft drives a Rolls-Royce Silver Cloud standard saloon, but for the interior shots a Daimler DS420 Limousine is used, which has a window behind the rear door, much more room in the back and a glass partition behind the front seats, which Croft uses to block out the noise of his children in the back.
When Perry and Croft have to change the opening titles, the familiar map and arrows are shown where the German troop movements form a capital H. However, this is just a black & white version of the title sequence used in the later colour episodes of series 3 onwards. The original animation used in series 1 and 2 had the arrows forming a different shape.
David Croft is shown smoking a pipe, however the real David Croft was strongly anti-smoking. In reality, it was Jimmy Perry who was the pipe-smoker.
Set in 1967 there is a scene at the BBC when actor Trevor Eve is called to see the executives, this is unlikely as Trevor Eve was only 16 years old in 1967.
Clive Dunn has fewer medal ribbons on his uniform than Lance Corporal Jones does in the real series. Also, one of them is the King George VI Coronation Medal, which Jones didn't have.
When Jimmy Perry drives up to David Croft's home, a satellite dish is visible on the side of the house.
Vehicle anachronisms: the period is 1967-68 but the cast travel to the set in a Plaxton Supreme-bodied Bristol LHS6L coach, which was introduced in 1975; Jimmy Perry drives a VW Beetle with an H suffix numberplate (August 1969 to July 1970); David Croft has a Lotus Elan in his driveway with a G suffix numberplate (August 1968 to July 1969) yet the scene takes place in 1967. Also, the Beetle model shown was not produced until 1969 and is shown as 'aged and well used' in the program, which would be impossible.