Continuity mistake: The clock in Denzel's apartment changes times during Del's first visit there, when he fools him into getting Del to paint his apartment.
Visible crew/equipment: When Del asks Mike if the pub is getting decorated and Mike says "in the near future", a boom mic is visible at the top of the screen. (00:26:40)
Revealing mistake: When Denzil's wife storms out of the room and slams the door behind her, you can see that the wall to the right of the door lurches forward under the pressure of the closing door.
Other mistake: Del and Denzil have been friends since their school days so when Del says he was once a painter and decorator for a year Denzil should've known he was lying straight away.
Continuity mistake: When Denzil's wife is in the kitchen slamming pots and pans, above Del and Rodney in the corner, Denzil's speaker, which was upside down, is now the right way up.
Chosen answer: An apparent long string of illnesses.