 The title is a reference to Andy 's a cappella group Here Comes Treble , which had previously been alluded to in the series , but never actually shown . " Here Comes Treble " guest stars Stephen Colbert as Andy 's college friend Broccoli Rob . Former NBC Entertainment co @-@ chairman Ben Silverman also guest stars as one of the investors at Jim 's meeting . With the filming of " Here Comes Treble " , the cast began realizing that the show was truly approaching its end . Wilson said , " it 's getting real . It 's like there 's a clock ticking " . Helms said that the fact that the episode was the last Halloween installment for the series is " a sad thing " . 
