When Lance first flourishes the bundle of £20 notes as a bribe the visible band is unmarked. In close-up it reads '£1000'.
In the debt collectors sketch Lisgoe says "You made £6 last month and your target was £500. Only £496 short" (not exact words but figures are). Either this was done on purpose or nobody in the crew knew that £500 minus £6 = £494 and not £496.
The structure of the fat-suit which Mark Gatiss uses to play Lance can be seen when he is pending over in his shop.