Continuity mistake: In the scene where Neville is telling Dennis he should find a woman, Dennis is getting dressed up in his suit to meet Dagmar. After Neville has finished talking, Dennis leaves the hut without a suitcase. But when he arrives at the hotel with Dagmar he is seen putting his case on the bed(Dagmar has one as well). It is clear that he has come straight from the hut, as he is telling Dagmar what Neville had told him before he left.
Last Rites - S1-E10
Continuity mistake: When Oz asks Bomber if he is interested in his porn deal, just before Bomber gets his foot broken, he tells Oz he has five kids. In series 3 episode 5, Bomber tells Lainie (the native American girl) when she asks if he has any family, that he has four children. Is not likely that any of the kids have died as he has just told her his wife had died and would probably have mentioned the loss of a child as well.
When the Boat Goes Out - S1-E13
Continuity mistake: During the first scene on the site, when the camera angle changes so does the weather, from overcast to bright sunshine; also at the same time the background noise from the building site changes as well.