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.
Fanon: Many people who saw the film were confused as to whether the German soldier that kills Corporal Mellish is also "Steamboat Willie." They are in fact, different soldiers. The soldier that kills Mellish has Waffen SS lapel insignia, while "Steamboat Willie" has the lapel insignia of an enlisted soldier in the Wehrmacht Heer. It doesn't really matter what you yourself think - if they were the same person it adds a little interesting twist, and if you felt bad for "Steamboat Willie" you can feel he survived the war.
Hell Is That Noise: The approaching German Tiger as the American soldiers were getting ready.
Retroactive Recognition: A lot of the younger actors, especially Matt Damon and Vin Diesel, were not yet megastars at the time this movie came out. Matt Damon had won an Oscar (albeit for Best Screenplay), but it may yet have been a flash in the pan. Spielberg is rightfully credited as helping jump-starting Diesel's career, writing the role specifically for him after seeing Diesel in his acclaimed short film.
And also, his Oscar is for writing. Hardly a guarantee of a career as an actor.
Jeremy Davies (Cpl. Upham) is Daniel Faraday in LOST.
Nathan Filion as Private James Ryan #1 ("James Frederick Ryan, Minnesota.")
Paul Giamatti and Bryan Cranston also have small roles and went on to become acclaimed actors.
Seinfeld Is Unfunny: Both on the giving (it's not the first movie to use a documentary-like depiction of war or realistic carnage, but the first popular one) and receiving ends (the influence on war movies or battle scenes in general, complaints about the patriotic\emotional tone of the scenes after Omaha Beach).