The opera singer seen near the end is Mark Donnelly, who also sings "O, Canada" regularly for the NHL team the Vancouver Canucks.
Gus mentions that they have solved over 47 cases. There have been exactly 47 episodes prior to this one.
Pierre Despereaux stays at The Gordon Mark Hotel. Gordon Mark is one of the producers of the series.
At one point, while in Despereaux's hotel room, Pierre Despereaux asks Shawn if he thought his 'Marco Ciccone' slippers were a gun. Marco Ciccone is actually the name of a cameraman in the Psych crew.
This episode takes place in Vancouver, Canada. Psych is filmed in Vancouver