Extradition: British Columbia - S4-E1
Character mistake: When Shawn is checking Ed's book of valuables, the crown that Shawn thinks Despereaux will steal, has a listed value of "950,000 - 1,000,00,000 USD." I guess it's really, really(!) valuable, enough that a whole new numbering system was made up for it. (00:30:55)
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.