Presuming you're the sort who'd buy an Edsel from a used car dealer, or oil stock from Billie Sol Estes and can extend that old willing suspension of disbelief to a rough and tumble World War II setting I think I may have just the movie for you.
The day and a half of the title represents the time allotted to a forward looking Nazi shrink (Rod Taylor) for extracting Allied invasion plans from an American intelligence officer (James Garner). His plot: drug Garner, then convince him (with a most elaborate hoax set) that he has had amnesia for six years, is in the tender loving hands of victorious Americans, and can only regain his memory through a "therapy" which consists of telling everything he can remember--i.e. the details of D-Day strategy. If this new-fangled ploy founders, Garner gets turned over to the pudgy S.S. man waiting in the wings, whose heart, you may be sure, is set on more traditional methods of persuasion.
As the hours elapse, we learn that the shrink is a fine fellow after all and, of course, that the difference between good Nazis and bad ones is simply that the former were raised in the USA until the age of sixteen and speak fluent English with no trace of an accent. We also learn that a pretty young nurse who has been tortured at Aunchwitz and is offered romance with a clashing Yankee, will have little loyalty to Hitler's cause.
If you can swallow so preposterous a platter of wiesserschnitzel, 36 hours will have you gagging on our popcorn. The success of the Normandy Landing is hardly in doubt, but Garner manages, with Eva Marie Saint in tow, to lead the Krauts a merry chase.
Also at the Paramout is a curious featurette "The Wandering Wind" about a chaotic hot-air balloon race across the Catalina Channel. After much colorful preparation, gay music, and chatty reportage we see a stiff wind carry the only female contestant's balloon out to sea through a cotton candy cloud. A drab black and white newsreel, clipped on at the end, shows a rescue boat recovering her drowned body.