Ted and Marshall plan one of their nostalgic road trips to a pizza place in Chicago, but Lily joins them, making Ted feel as if the "bro time" isn't there. Meanwhile, Robin is at risk for deportation, and Barney helps her cram for the U.S. citizenship test.
This episode provides examples of:
- Canada, Eh?: The night before her citizenship test, Robin gets drunk at the Hoser Hut and ends up traveling to Toronto. When Barney tracks her down, they go to a Tim Horton's where Robin feels alienated by everyone's friendliness and hockey references, making her question if she's even a real Canadian anymore after living in America so long.
- Eagleland: Barney's citizenship test for Robin consists of quizzing her on various facets of American pop culture.Barney: Question one: (holds up a picture of the Queen) Who is this?
Robin: Queen Elizabeth the Second.
Barney: No, the answer is Elton John. Question two: What the hell is this?
Robin: Oh, curling. It's a sport played by—
Barney: Wrong. The answer we were looking for was, "I don't care, it's dumb. Let's go buy something that's bad for us then sue the people who made it!" That's American, Robin.
- The Food Poisoning Incident: Ted tricks Marshall into ditching Lily at a bed-and-breakfast so they can go to their favorite (unsanitary) pizza place before it gets shut down, but Marshall feels guilty and they go back to find that the B&B has pampered Lily into such a deep state of relaxation she didn't even notice they were gone. In any case, within minutes Ted and Marshall get violently sick from the pizza.Marshall: Baby, cut it out of me. Cut it out!
- Friend Versus Lover: Ted feels that Marshall has been ignoring him since he got married.
- G-Rated Drug: Tantrum. Which is technically a soda, but with high levels of caffeine enough to render someone hyper. According to Future Ted, it was eventually banned in the United States.
- Gilligan Cut: Marshall could not bear the thought of leaving Lily alone after Ted kidnaps him to go to Chicago. At first.Marshall: What are you doing? We can't just leave Lily.
Ted: She's got a backrub and a crumpet, she'll be fine. Relax. Have some fun.Marshall: I just abandoned my wife. How am I supposed to have fun?(4 minutes later, cut to the two jamming to "I'm Gonna Be (500 Miles)" by The Proclaimers)Ted: Hey, you really think Lily is pissed?
Marshall: (laughing while drunk on Tantrum) If she's pissed, she's pissed.
- Pun-Based Title/Spoiler Title: Robin is "dueling" with herself about which country she'd rather be a citizen of; the "duel/dual" homonym spoils her decision.
- Reality Ensues: Robin getting into a fight with a guy in a bar leads to him filing assault charges. She decides to become a US citizen to avoid getting deported.
- Reality Is Unrealistic: Barney is astonished that the Canadian five-dollar bill is blue and has kids playing hockey on the back. Which it does.Barney: It's like you want us to make fun of you!
- Series Continuity Error: Flashbacks show Ted and Marshall driving to Chicago sustained on only jerky and Tantrum. However, a point was made in "Arrivederci, Fiero" that Marshall has always had a very firm rule about not allowing food or drink in his car, not even groceries.
- Sickeningly Sweethearts: Marshall and Lily have reached a point in their marriage that they exclusively refer to themselves as "we" and not "I".
- Take a Third Option: Robin, thinking she's too American for Canada and too Canadian for America, decides that Both Sides Have a Point and opts for dual citizenship.Robin: Instead of being a woman with no country, I'm gonna be a woman with two.
- Third Wheel: Ted, Marshall, and Lily's sideplot involves Ted feeling like a third wheel to Lily and Marshall since their wedding. In the episode, Ted and Marshall take a road trip to Chicago like they used to in college, but Ted is irritated that Marshall invited Lily who spoils the experience with her constant pee breaks and cheesy audiobook.