In the discussion about Will's lineage, Oliver says that he is "100% Irish, through and through". Martin Short is indeed of mostly Irish descent: his father was a first-generation Irish immigrant, a Northern Irish Catholic who fled to Canada as a stowaway during the Irish War of Independence, and his mother was of English and Irish ancestry. The Irish brogue that Short uses in the scene is based on his father's voice.
In the Son of Sam game, the victims are blondes. The real Son of Sam primarily targeted brunettes.
The Son of Sam game really is a children's game.
In the UK it's called Murder in the Dark, and was originally played without the cards; everyone just closed their eyes while the murderer was chosen.