These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Examples from the movie
Fridge Brilliance: David's car was given a nice splattering of gasoline on the hood when the gas attendant got sloppy with the hose. This is what caught on fire, not the car itself.
Fridge Horror: Just before the truck goes over the cliff and crashes in the end, the door to driver's seat is open and the driver is missing... Still, he's nowhere to be found and there's a nice blood stain on his steering wheel.
Look at the truck's front, with all the license plates and notches carved in the headlights..
Moral Event Horizon: The truck is just tormenting Mann... until it tries to run him down in the phone booth and destroys the cages and property at the gas station. At this point it is okay that the truck is destroyed at the end.
Padding: While not as bad as other shows that were on the air back then, Duel holds the dubious distinction of being one of the few shows to end an episode after the players had locked in their answers, thus forcing everyone to wait until the next show to see if they were right.
What an Idiot: Possibly the worst time to fall into this trope is on the aforementioned Moment Of Awesome. The Duel could've kept going with a true one-vs-one All or Nothing, if Jennifer had known who the members of The Rolling Stones were. Jennifer put her chips on Keith Richards, Charlie Watts... and Robert Plantnote Hint: he wasn't a member of the Stones. Gabriel put his chip on the other Rolling Stone: Mick Jagger, which won him half a million dollars.