Book Ends: Murdoch shows his alienation from his job by throwing his police badge into a river. Jack London gives it back to him right before he returns to Toronto, having found it in the water.
Clear Their Name: Murdoch does this for his landlady Elizabeth Bryant, who's been framed for murder.
Gold Fever: The episode is set near the end of the Canadian gold rush. Gold also proves to tie into the motive for the murder Murdoch ends up investigating: the two victims were the last holdouts preventing a dredging operation from setting up in the area, which would at least temporarily revitalize the withering town. One of the victims also owned a local hotel, so by killing her and framing her competitor for her murder, the killer planned to end up owning the only hotel in the area and cleaning up on profits from the miners and workers of the dredging operation.
He's Back!: Murdoch signifies this by putting on his traditional detective's suit and Homburg hat when he resolves to help Elizabeth.
Mr. Exposition: Jack London explains Isaac McKay's dredging plans to Murdoch, Elizabeth and the audience, including how they could relate to the murder.
I Never Said It Was Poison: Serves as a key clue to Crabtree's investigation of a murder when the perpetrator slips and reveals they know the victim was shot.
Red Herring: Mining man Isaac McKay is poised to make a huge profit from dredging the creek (a project the murder victims were obstructing), has his bodyguards pick a fight with Murdoch when he first asks to examine the body and pointedly asks Murdoch to leave town. He doesn't stoop to dishonest methods to get his way, though, and is innocent.
The Watson: A young Jack London serves as this to Murdoch, even returning his badge when Murdoch tossed it into a river.
What the Hell, Hero?: Elizabeth tears a strip off Murdoch when he initially refuses to help her, saying he was no longer a detective.
