In external shot of the Planet Express building, a truck can be seen carrying a Wreck-it-Ralph arcade game. Wreck-It Ralph (2012) was directed by Rich Moore, who previously directed five episodes of the show.
The situation in which Bender and Fry find themselves at the end, after murdering the businessman (choosing between remaining silent about their crime and risking a chance of going to jail if they are caught, or betraying the other in order to get a reward and a full pardon), is a logical problem in Game Theory known as the Prisoner's Dilemma, used to show the paradoxical results of the Rational Choice Model.
In the external shot of the Discount Spy Store, as Fry is walking up a fish wearing Professor Wernstrom's Reverse Scuba Suit from A Big Piece of Garbage (1999) can be seen walking out of frame.
The combination Leela uses to open the weapons safe is 615.