The signature tune for Pat Mustard's entrance and exit is Penthouse Suite by Syd Dale. Also used in the Tarrant on TV series.
The top speed on the milkvan is seven mph.
Rather coincidentally this episode is called "Speed 3" it is in season 3 and it is episode 3.
There is a red sign on Dougal's Milk Float that says "Milkmen do it on your Doorstep" that has the words "do it" blacked out once Dougal takes over as the driver.