Strangers on the Shore - S9-E2
Other mistake: Boycie asks to sleep in the Trotter's flat after being chucked out of his house and not allowed back in due to a gas leak. He states "I was going to check into a hotel, but I've left everything in the house; wallet, credit card, car keys, the lot... so all I've got is what I'm wearing." He isn't shown to be carrying any luggage. Later in the episode, Raquel complains that Boycie keeps putting on the hair gel that Del added onion puree to at the start of the episode. How was Boycie able to get his hair gel that was in his gas-filled house? One could propose that he asked the firefighters to receive it, but why wouldn't he also ask them to retrieve his wallet/credit card so that he can book into a hotel rather than sleeping on the sofa in the Trotter's overcrowded flat? (00:58:00 - 01:05:00)
Other mistake: When Del is cutting the turkey, Watch Grandad indiscretely look at the camera to see if it's his cue. (00:05:05)
Miami Twice: Oh to Be in England - S7-E9
Other mistake: Del had the smuggler's letter in his pocket when he fell in the swamp. When he takes it out at the rangers station, it's perfectly dry. Surely, it should be soaked.
Big Brother - S1-E1
Other mistake: When Grandad is playing draughts on the talking chess game, the voice on the game talks before he presses the button.
Other mistake: At the end, Rodney is looking at a map to see where Del ended up. But he didn't know where he had landed at this point so there was no point.
Other mistake: After Del-boy is finished filling the first set of water bottles with the hose, he moves the rig and sets up some new ones. Now, when he pours, the water doesn't go into the bottles, but rather pours over the side. Despite this, Del continues working as though everything is fine. (00:43:45)
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.
Chosen answer: An apparent long string of illnesses.