Clare is worried that they will get into big trouble for doing drugs. Besides being illegal she says that they can lose their kneecaps if they get caught. James seems unable to believe this. However, Clare wasn't exaggerating, during "TheTroubles" in the '90's in Northern Ireland, the IRA took it upon themselves to act as the police. Drug dealers and habitual drug addicts were often punished with gun shots to their kneecaps.
At the wedding reception the DJ plays "Rock the Boat" and everyone rushes to sit on the floor and position themselves in rows to dance like they are in a rowboat. This is a common event at Irish weddings where the song and the dance routine have been popular for a long time.
James says he's never seen a dead body before, which was probably true before he came to Derry, but there was the nun that died in detention in the first episode.
Erin has a rainbow shirt on when she's in the kitchen, as a tribute to Clare.