Aluminium Christmas Trees: It's not uncommon nowadays to find people who think the concept of a "dance marathon" was completely invented by McCoy (or at the very least an exaggeration of a typical dance contest). In reality, dance marathons such as the one in the novel were a fairly common feature of Depression-era America, and were just as brutal on the contestants.
Germans Love David Hasselhoff: The novel was not very popular in the United States, Horace McCoy's home country, but it was very popular in French existential circles (even though it was not translated into French until 1946); among its fans was screenwriter and director Roger Vadim, who persuaded his wife, Jane Fonda, to accept the role of Gloria in the film adaptation despite her initial reservations.
No Such Thing as Bad Publicity: In-universe. One of the contestants turns out to be an escaped murderer from Illinois who is recognized by a couple of detectives in the audience, arrested, and taken away. Socks the promoter is initially angry at having a criminal mixed up with the marathon, but after a newspaper article about the arrest draws in bigger crowds he states that it “was the best break we ever had”.
Values Dissonance: In the present day, encouraging a depressed person's suicidal ideation would be viewed as insensitive and irresponsible. Of course, in the Depression there was precious little resources for people with mental health problems.
Values Resonance: The theme of financially desperate people willing to degrade and endanger themselves for survival and the sadistic glee others get out of seeing it is arguably even more relevant in the 2010's and 20's as economic downturns, the rise in rent and education, crippling medical debt and massive wealth inequality along with the rise of reality television has led to many people willing to do anything they need to just to survive and see victories on such shows as the only way to do so.
Vindicated by History: The novel was poorly received when it was published, but subsequently enjoyed a cult following.
Adaptation Displacement: The film tends to be better-received than the novel is, probably due to the fact that the former can expand more easily on the themes of the very short book.
Award Snub: This film holds the dubious distinction of having the most Academy Award nominations (nine) of any title that didn't get a Best Picture nomination. And of those nominees, only Gig Young (Best Supporting Actor) took a statue home.
Harsher in Hindsight: The film ends with Robert helping Gloria to shoot herself. In 1978, Gig Young, who played Rocky in the film, shot his wife Kim Schmidt and then himself; no motive for the apparent murder-suicide was ever established.
Likely intentionally invoked when Rocky announces that Helen Twelvetrees and Ross Alexander are in the audience. Both were Hollywood actors who also wound up dying by suicide.
Nightmare Fuel: The derbies. Both of them. In the first, the chaos slowly builds throughout the race until all the contestants are in a state of disturbingly realistic panic and exhaustion, complete with hysterical screaming and crying. In the second, we're thrown right in to the midpoint of the derby when everyone is already fully exhausted. The scene then slows down while a creepy carousel-like version of the derby's theme music ("California, Here I Come" by Bud DeSylva, Joseph Meyer, and Al Jolson) plays, only for things to snap back again to full-speed as Harry begins wheezing and gasping and clutching his chest. Add to that the clear implication that Gloria finished the race by dragging his corpse on her back for the last half-lap, and it's a truly horrifying scene to watch.
