The Curse of the Jade Scorpion

It was a take on a bunch of film noirs from the 1940's (one that most likely influenced this one was The Big Sleep). The rest of the leading cast was Dan Aykroyd, the manager of an insurance firm in which Allen works, and Helen Hunt, Aykroyd's secretary who always has time to insult Allen (if you know anything about old films, you'll probably realize just how close these two are, and I don't mean just in the office).

The film follows this insurance firm as they all try to search for a bunch of lost jewels, not realizing that someone in the office is borderline guilty. The group goes to a nightclub to celebrate Wallace Shawn's 50th birthday, and the entertainment is a "magician" who ends up putting both Allen and Hunt under hypnosis and convinces them to do his will and also that they're in love with each other, with only the utterance of two words: "Madagascar" and "Constantinople" (gee, it'd be a shame if these two words were uttered later in the movie to advance the plot).