A pretty minor one, considering it lost to a good movie like Chariots of Fire, and was up against a major epic like Reds and well-received dramas On Golden Pond and Atlantic City. But of those films, Raiders had made a more lasting impact (on summer blockbusters, adventure films as a respectable money-making genre, Harrison Ford's bankability outside of Star Wars, etc.)
Spielberg losing Best Director to actor Warren Beatty (for Reds) is an arguable case. Those who support Spielberg note that, while Beatty is a respectable director with a decent career, Spielberg was at the height of his powers directing incredibly well-made action movies. However, this is refuted by some who find Reds to be a directorial achievement above all else (not to mention a labor of love that took Beatty years to get off the ground), and many cite his win (the only Oscar he ever earned in his long career) as one that was justified both in context and by merit. It would get worse when Spielberg lost the following year over ET (after which is when he started making serious Drama movies).
Crosses the Line Twice: Spielberg likes to mention regarding this film that Nazis make ideal movie villains, as you can do any horrifically violent thing you want to them and no one will get upset.
"Funny Aneurysm" Moment: As Indy speaks with Marcus while packing for his trip, Indy says "You sound just like my mother" as he dismissively speaks of the Ark's powers (which turn out to be very real). In Indiana Jones and the Last Crusade, we learn that Indy's mother passed away during his childhood, and his relationship with his father fell apart afterwards. And he grew to hate his father for being so obsessed with the Holy Grail, rather than focusing upon Indy.
Iconic Character, Forgotten Title: Upon its original run, the movie did not follow the "Indiana Jones and the X" naming scheme that sequels did, simply titled Raiders of the Lost Ark. However in later home media releases it was retrofitted, ie: Indiana Jones and the Raiders of the Lost Ark.