The briefcase held the actual, original MacGuffin and the actual, original Chekhov's gun--which was never fired in the movie. The former was the treasure that

The briefcase held the actual, original MacGuffin and the actual, original Chekhov's gun--which was never fired in the movie. The former was the treasure that had been used as a nonspecific plot device by Sophocles, Menander, and an unbroken line of storytellers, through Shakespeare, and ending with Alfred Hitchcock, George Lucas, and Quentin Tarantino. The latter had a more recent origin, but somehow ended up in Tarantino's possession without him knowing of its significance. It is somewhat obvious that Tarantino lost the plot devices some time after production, as they reappeared in fused form 6 years later in "Dude, Where's My Car?"