After having sex with the landlady, Duval finds her in the bathtub brutally murdered. He collects the used bed sheets and methodically wipes clean all his fingerprints. Then he takes the used condom throwing it in the toilet seat, closes the lid and flushes once. Anyone who has ever tried this, knows a used condom never flushes on first try having an air bubble inside.
Despite being set in 2002 we see Dervla Kirwin drive past a Vauxhall Astra H SRI XP, a car not released until 2005MY.