Tobias is painting Shawn's portrait in right 3/4 profile but Shawn is posing in left 3/4 profile.
Parker's receptionist's Sudoku puzzle has numerous mistakes. For example, one row with two 6's and two 9's and two columns with two 7's.
When Gus goes to talk to the Doctor about being his pharmaceutical rep, Shawn stops him and tells him not to step on the corpse's head. When it cuts to the wide shot they are standing at the corpse's feet.