Out of the three leads, Homer is the one who gets the most love. He's an Iron Woobie who has all the film's most memorable scenes, and provides most of the Tear Jerkers. His actor Harold Russell was even awarded two Oscars because they didn't think he'd win the one he was nominated for.
Al getting drunk on his first night back home, going out with his wife and daughter. He ends up roleplaying that he's still overseas and Milly is another woman. She snarkily plays along.
"You didn't tell me you were married."
Woody Merill sums it up nicely when Peggy asks what's wrong with Fred and Marie's marriage.
"Nothing, except one slight detail. They don't like each other."
Peggy later (after Fred has broken it off with her) grumpily saying her career as a home wrecker is now over.
Ho Yay: Fred and Al end up drunkenly cuddling each other in the back of the car. Millie jokes "what a lovely couple they make."
Jerkass Woobie: Luella was incredibly insensitive when she led the neighbourhood kids to spy on Homer's hooks, but you absolutely feel for the poor girl after Homer's outburst. She's clearly feeling horrible about what just happened.
Signature Scene: Homer losing his temper with some kids trying to get a peek at his hooks, and breaking them through a window.
Some Anvils Need to Be Dropped: At the time this was the first film to really show how badly the soldiers had it when they returned home. After ages of the familiar Why We Fight films stressing the Black and White Morality of the war, this told audiences about the difficulties returning soldiers faced.
Strawman Has a Point: One guy in a diner tells Homer that the military basically duped him and cost him his hands. While one could hardly blame him for being upset, since the Nazis and Japanese might have done more damage, had he not been in the war, there is no debating that he still would have had his limbs intact (to say nothing of the fact that the conflict with the Japanese was pretty much resolved with nukes and Hitler committed suicide, so U.S. troops might not have been needed).
The scene with Homer returning home, where his own mother gasps in horror upon seeing his metal hooks. And Homer flashes a pained expression across his face...
A real life example: The man who played Homer went bankrupt after this movie and ended up having to sell his Oscars.
Towards the end, as Fred finds himself in the bombers' graveyard, row upon row of rusting hulks no longer needed with the war over, symbolizing his own worthlessness as a war hero with nowhere else to go. When he crawls into one wreck to relive yet another flashback, you're crying for him. Subverted when he's discovered by a guy overseeing that graveyard who's starting a project to break the hulks down into metal housing for the families of returning war vets. Fred finds out they're hiring.
Unintentionally Sympathetic: It's hard not to feel sorry for Marie, given that she and Fred were a Fourth Date Marriage and part of the reason she's so unhappy is because he's not letting her work. Yeah she's having affairs but she eventually calls for a divorce and frees Fred up to get with Peggy.
To modern viewers it can seem pretty odd how little attention Al's obvious alcoholism gets.
Subverted with Fred and Marie's marriage. Fred insists she stop working even when they become too broke to go out any more. It's used to show Fred as an idiot and it's a hint that there are cracks in the marriage already.
Values Resonance: The story of soldiers having trouble readjusting to their lives before the war still holds up, especially as the world they left is now different and they have to try and find their place in it - something that's still relevant today.