Another version of the incidental music heard while Simon drives around collecting items (such as fireworks) is heard in Living in Harmony (1967), an episode of The Saint (1962). The composer is Edwin Astley.
When Spring's wife speaks with him in court, and talks in Russian, what she says; means, 'the mail's in the mailbox'.
The garage where Simon parks the van in a garage is on Ennismore Mews, near Hyde Park in London.