The film was a huge hit in cinemas, and became the third-highest grossing film of 1972. The film won the Writers Guild of America 1973 "Best Comedy Written Directly for the Screen" award for writers Buck Henry, David Newman and Robert Benton. It was placed at number 61 on the list of 100 greatest comedies published by the American Film Institute, and at number 68 on the AFI's 100 Years... 100 Passions.
Howard, Eunice, Mrs. Van Hoskins, and Mr. Smith all happen to check into the Hotel Bristol at the same time, whereupon Judy lodges herself there without paying and begins pursuing Howard (to his bewilderment), two hotel employees (Sorrell Booke and Stefan Gierasch) attempt to steal the jewels belonging to Mrs. Van Hoskins, and Mr. Jones attempts to get the bag belonging to Mr. Smith. Over the course of the evening, the bags get switched willy-nilly from room to room as the four parties unwittingly take one another's suitcases. Howard ends up with the jewels, Judy with the documents, Mr. Smith with the clothes, and the thieves end up with the rocks. Few people ever actually open the bags to confirm that what they think they have is what they actually possess. Meanwhile, Judy manages both to secure the grant for Howard while masquerading as Eunice and to destroy his hotel room. The following day, everyone makes their way to Mr. Larrabee's home where a shooting ensues, Howard and Judy take all the bags and are chased up and down the hills of San Francisco by the thieves, Mr. Smith, Mr. Jones, Eunice, Simon, Larabee and a few roped-in bystanders. They go through Chinatown, down Lombard Street, and eventually into San Francisco Bay. All the protagonists finally end up in court, under the gavel of a world-weary and curmudgeonly judge (Liam Dunn) who, improbably, turns out to be Judy's father.
In the end, everything is cleared up, Mrs. Van Hoskins pays the considerable damages in Howard's name with the reward money he would have received for the return of her jewels, the hotel thieves are forced to flee the country and the papers are put back in the hands of the government (though perhaps not for long...). More importantly, Judy exposes Simon as a fraud and plagiarist, Eunice leaves Howard for Larabee and Judy announces she is taking one more pass at college — studying Music History at the Iowa Conservatory of Music. The film ends a suitably romantic (and silly) note as Howard and Judy share an airborne kiss while their in-flight movie shows the Bugs Bunny cartoon that gave the film its name.
The final scene in the film makes fun of "Love means never having to say you're sorry," a famous line from Love Story, a highly successful tear-jerker in which O'Neal had starred two years earlier. Howard reacts to the line when Judy says it by replying, deadpan, "That's the dumbest thing I've ever heard." Ryan O'Neal's mannerisms, from the very first shot of him staring vacantly into space, are modelled on those of Harold Lloyd.
Also in the final scene is an oblique tribute to actor Cary Grant, star of the screwball classic "Bringing Up Baby". As Howard looks for Judy, he says "Judy?....Judy?....Judy?", a phrase often used by impressionists "doing" Cary Grant (although Grant never actually said the line).
Randy Quaid appears in a small role, intentionally miscast as a professor of music, with a thick Texas accent.
The movie features a number of actors who have featured in Mel Brooks films - Madeline Kahn (Blazing Saddles, Young Frankenstein, High Anxiety, History of the World Part I), Kenneth Mars (The Producers, Young Frankenstein), Liam Dunn (Blazing Saddles, Young Frankenstein), and John Hillerman (Blazing Saddles).
The San Francisco setting was chosen to allow an elaborate comic spoof of the San Francisco car chase in the hit 1968 movie Bullitt . The classic "plate glass" scene was filmed at Balboa and 23rd Avenue in the Richmond District. The director did not get permission from the city to drive cars down the concrete steps in Alta Plaza Park in San Francisco; these were badly damaged during filming and still show the scars today. At the end of the car chase, almost everyone ends up floundering in San Francisco Bay — except O'Neal and Streisand, comfortably afloat in their Volkswagen Beetle. This was a play on Volkswagen print and TV ads from a few years earlier that championed the Beetle's remarkable (and real) ability to float on water.
The final scene on board the airplane shows Streisand looking out the righthand window showing the Marina District and the (now demolished) Embarcadero Freeway. An airplane having just taken off from San Francisco International Airport would not have been flying over the city in that direction.
About two-thirds of the way into the film, Howard accompanies Judy at the piano as she sings the beginning of "As Time Goes By" (made famous in the film Casablanca). The scene includes Streisand imitating Humphrey Bogart with the line, "Of all the gin joints, in all the towns, in all the world....he walks into mine. Play it, Sam."
Musical jokes abound throughout the film. Over-the-top Muzac-styled elevator music featuring Cole Porter's songs are used throughout the hotel scenes. In the chase scene, a Chinese marching band is inexplicably playing the Mexican tune "La Cucaracha" on German glockenspiels. At the American Musicologists' banquet, themes from Thoinot Arbeau's Orchésographie can be heard in the background, incongruously played on a Hammond organ and a sitar.
The Bugs Bunny number — derived from his characteristic tagline — that gives the movie its title, appears as well, with the original animation, in the last scene. "Please Don't Talk about Me When I'm Gone", an old Tin Pan Alley hit which had appeared in Looney Toons cartoon One Froggy Evening, can be heard instrumentally during the opening scene in the airport.