My recollection (which of course is spot-on almost always ) was that Spade referred to Gutman in the movie any number of times as "Fat Man."
Interestingly my first thought for this FJ was the "black bird," which I also thought I remembered as a reference to the falcon once or more in the movie (anyone? corroboration? or rebuttal? I'm not certain on this one). However, the "black bird" weapon was the stealth bomber not produced until decades after 1945 so I shortly went looking for another eponym and stumbled onto fat man shortly and in time.
What struck me in this episode (besides watching Jason stumble badly out of the gate and rebound quite nicely) was how both of his competitors wagered so awfully in FJ. Barbara needed to wager $1 more and answer correctly to lock Jon out of the extra thou. If he had answered correctly she would have finished in 3rd after her math error threw away the extra thousand bucks. Jon, meanwhile, wagered all-in which would usually be futile in a trailing position and would have cost him second place in the event of a double-miss. No one seems interested in learning Wagering 101. Or math.
Meanwhile I ran "M" Ports, which included Messina, which was the answer to a clue on a recent online contestant quiz.
And yeah, it must be really sweet when you're in position to make a killing and salt the game away by landing on a DD, and the category is right in your sweet spot, as it was for Jason as he landed on Classic Metal. When the stars align....