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.
Crowning Moment of Awesome: It's a very perverse and depressing one, but Mother taking down the Germans during the "battle" shows that, despite spending the movie in a state of Heroic BSOD, he is capable of bravery when his buddies are in danger. Or when he thinks they are.
Crowning Moment of Heartwarming: The middle act, before it becomes a Tearjerker. The Americans and Germans setting aside their differences, making friends, getting in a snowball fight and singing Christmas Carols.
Hilarious in Hindsight: Will describes the incompetent Major Griffin as a former mortician apparently racking up business for his army counterparts. John C. McGinley, who played Griffin, stars as a doctor in Scrubs. One of the characters in the latter is an incompetent doctor who becomes a mortician.
It Was His Sled: Go ahead, find someone who don't know how the deal with the Germans ended. People are more likely to know about the bloody mess created by Mother than anything else from the film.
Nightmare Fuel: Posthumous Character Eddie, who loses his left arm and suffers severe facial wounds in an ill-fated patrol before the events of the movie. A flashback shows him in a field hospital, heavily bandaged, with one open eye staring hauntingly into the camera, and by default, the viewer's soul. We are not shown his face, which somehow makes it worse.
The dead American and German, embraced by frostbite, is just eerie...
The "battle" sparking a firefight that leads to all the Germans being killed.
Father Mundy's death.
The Bittersweet Ending: The four survivors of Intelligence never make contact again when the war ends, with the exception of Mother sending a lone $10 dollar bill to Will every Christmas, to pay off a bet.