Factual error: Cops can't force someone to leave a park because they're male and have no children.
Black and Tan: A Crime of Fashion - S2-E15
Factual error: In the flashback at the beginning of the episode, Shawn is wearing a Knight Rider T-shirt. This flashback takes place in the 80's, but the art printed on the T-shirt is a picture-perfect copy of the cover art from the US DVD release of Knight Rider Season 3 - this DVD set (and the cover art style/arrangement) was not released until 2006: http://en.wikipedia.org/wiki/Knight_Rider_%28season_3%29.
Chosen answer: "Psych: The Musical" was supposed to air during the regular season 7 schedule, before Chief Vick is suspended and Jules discovers Shawn's lie, but the network decided to push it back to air as a special episode, sort of as a tie in with the holiday season and a lead in to season 8, which was to begin only a couple of months later.