The scene where Gene receives a letter that his dog has died and Snafu tries to comfort him, leaning against his shoulder
Chuckler's gentle "aww, buddy" when he sees that Leckie is sick again. It's more prevalent in Leckie's memoir, he was basically the Team Mom of Leckie's gang, and had more than a few sweet moments when it came to the boys.
John and Lena's wedding, and basically everything about them
Leckie bonding with Stella's family in Melbourne
Sledge cradling the dying woman on Okinawa, instead of mercy-killing her. A bit of a tearjerker as well..
Sid visiting Gene's parents after being shipped home and assuring them (rather untruthfully) that he wasn't worried about Gene's safety because he was with good men
Gene coming home to his parents
Snafu awkwardly thanking a departing Burgie "for doin' all you did to keep us from gettin' our fools heads shot off" on the train home
Leckie and Vera's awkward-but-sweet date once he returns home, especially considering that he married her in real life
Lieutenant Colonel Lewis "Chesty" Puller saluting Basilone when he gets the Medal of Honor (Basilone said in real life that it was one of the proudest moments of his life)
Normally, the lower-ranking man salutes the higher-ranking one, and holds the salute until the superior returns it. However, any man wearing the Medal of Honor gets saluted by everybody, from the lowest private to five-star General. Strictly speaking, they are saluting the medal and the act that earned it.
Runner calling Leckie Peaches after they're both injured and brought on the same hospital ship. Also when Leckie starts to get choked up while explaining that he meant to come back for Runner, but couldn't, and Runner tells him that he understands.
Leckie: (tearing up) I tried to get a Corpsman. I tried to get back to you.
Runner: I know. Lucky? (Leckie looks at him) I know.
Captain Ack-Ack admitting that he's comforted by the thought that his father, who manages a textile mill that makes fabric for the Military, had something to do with the blankets he and his men sleep in. Also makes the moment when his dead body is wrapped in a blanket that much more if a Tear Jerker
A Marine named Daniels is delusional after crossing the airfield at Peleliu and is counting over and over invisible Japanese soldiers as the unit stops for the night. He gets an order to go on a patrol and can't understand what is being asked of him. Hanney starts to tear into him, but Ack-Ack stops him, says he needs him for the night and gives the order to someone else. He then asks Daniels to come count bandages, and when Daniels insists he needs to count the "soldiers," Ack-Ack doesn't correct, he just gently tells him that someone else can do it. It's easy to see why the men under his command saw him as A Father to His Men.
For all that Snafu makes fun of Peck, it is rather touching seeing him comfort Peck after his meltdown.
When the men return from the Guadalcanal campaign, they wonder whether what they did was worth it. Then when they get coffee from a cook, the cook informs them that their exploits are front page news all over America and everyone back home considers them heroes.
A Real Life example: Sledge's family was so impressed by John Mazzello's portrayal of Gene, that they gave him the pipe Sledge carried during the war.