Continuity: At the start of the episode when Rodney and Grandad are arguing, Del walks past Grandad and past the chair next to him, yet in the next shot he walks past the chair again.
Deliberate "mistake": When Del is on the phone to Dougie Sadler, he says, "How's your luck pal? Terrific. Family? Super". There is no way that Dougie could have replied to those questions given the speed Del was speaking.