1964, Tokyo. Wealthy industrialist Sir William Rutland (Grant) has arrived in Tokyo to conduct some business. Unfortunately for Sir William, he has arrived in town a few days early, and there are no hotel rooms to be had, the whole city being full of visitors for the soon-to-begin 1964 Olympic Games. With Airbnb and Couchsurfing.com still decades in the future, William finds a posted notice for a room to rent at the embassy. He finds that room to be in an apartment occupied by one Christine Easton (Eggar), an attractive young lady. Christine is shocked and embarrassed by finding an older man moving into her apartment, but the Happily Married William wants nothing more than a room, and gets her to let him stay by sheer force of personality.
The situation becomes more complicated when American athlete Steve Davis (Hutton) also arrives in Tokyo early and also can't find a room, the athlete housing not yet being available. William meets Steve and takes it upon himself to invite Steve to the cramped apartment he's sharing with Christine. Soon romantic sparks start to fly between Steve and Christine, and William decides to get them together—which also involves breaking up Christine's engagement to stuffy British embassy official Julius P. Haversack (John Standing).
Notable as Cary Grant's last film. Grant, then 62 years old, was too old to play romantic leads anymore and chose to retire rather than play supporting parts. Among the supporting players are Miiko Taka, who played the female lead in Marlon Brando film Sayonara, and a pre-Star Trek George Takei, who pops up near the end as a Japanese police captain.
- Blunt "Yes": William can't resist poking into Steve's life.Steve: Can't you stop being nosy for one minute?
William: I don't think so.
- The Bore: Julius, who will go on and on and on about trivial government business like reciprocal tariffs, and has an idea of writing a memoir that sounds incredibly dull. William gets Julius talking about his book to distract him while Steve and Christine are together, but he has to watch a portable TV while Julius drones on.
- Celebrity Paradox: Some kids watch a Hong Kong Dub of The Man from Laramie on Japanese TV. So James Stewart exists in this universe, which raises the question of whether or not The Philadelphia Story exists in this universe and why the guy who played C.K. Dexter Haven looks so much like Sir William.
- Conversation Cut: Catherine finally tries to quash the idea that William is going to room with her by saying "Mr. Rutland, this is impossible!" This is followed by a cut to Christine's name on the buzzer outside, with "Rutland" handwritten next to the typed "Easton."
- Foreshadowing: The title. A Running Gag throughout has Steve refusing to say what his Olympic event is, seemingly vaguely embarrassed by it. It turns out he's a racewalker. The title of the movie, of course, is Walk, Don't Run.
- Hypocritical Humor: After hyperbolically praising the exotic (then-exotic, anyway) entrees at dinner—seaweed, chicken teriyaki, octopus—William has the waitress bring him ham and eggs.
- Jackhammered Conversation: During a scene where William and Steve seem to be wondering about whether Catherine is a virgin or not, the most sensitive dialogue is masked by stuff like a piping tea kettle or a running faucet as they putter about making breakfast.
- Japanese Politeness: A gag in the opening scene in which no fewer than five hotel workers come to William at the hotel desk, all apologizing profusely for his room not being available, all explaining that he's there early and rooms are sold out for the Olympics.
- The Matchmaker: William takes on this role, working hard to get Catherine and Steve together.
- The Remake: Of 1943 film The More the Merrier, in which the housing shortage premise is tied to World War II and various military and government types descending on Washington, DC.
- Romantic False Lead: Boring, colorless Julius, obviously there just to be displaced by Steve.
- Rom Com Job: Steve's an architect and an Olympic athlete as well.
- Running Gag: Steve identifying himself as an Olympic athlete, but being strangely reluctant to say what his event is, even when he's asked multiple times. The ending of the movie reveals that his event is that goofiest of sports, racewalking.
- Serious Business: A young unmarried woman hosting a man in her apartment is apparently a huge huge deal. How huge? A newspaperman is going to write a story about it, which leads everyone involved to decide that Steve and Christine have to get married so that her fiancé Julius can avoid social embarrassment and damage to his career. (Major Unintentional Period Piece here, as it's impossible to imagine a film with this premise getting made just a few years later in the swinging 1970s.)
- Super OCD: Christine, especially with regards to her morning routine, in which she has down-to-the-minute time frames for each activity."At 7:32, I clean my teeth."