Several men graphically drown in the water due to their gear packs weighing them down, while trying to get them off.
One of the landing craft unknowingly drops its ramp right in middle of the field of fire from an MG nest, not a single man aboard makes it to the beach alive.
James "Scotty" Doohan, D-Day vet who lost a middle finger and was shot during the operation, in an interview, when asked about the opening sequence remarked simply "Yes, that's exactly what it was like." Well... Fuck.
The sound of the approaching German Tiger was accurate enough to give many veterans in the audience flashbacks.
The messy results of when the Germans use a 20MM anti-aircraft cannon on exposed infantry. You could argue the guy who got his head blown off at least didn't suffer, the rest actually survive getting hit and can only writhe on the ground in agony until they're noticed and finished off.
There's also the scene where Mellish gets into a hand-to-hand fight with an SS soldier, and loses, with the German overpowering him with his knife sinking the blade slowly into Mellish's chest as he convulses and gasps and then goes limp as his life leaves him. Worse, the soldier leaning in close and whispering to him in German: "Give up! You have no chance, let's end this! [...] It's much easier for you, it's much easier for you. You'll see, it will be over quickly. Shhh... Shhh..."
Even worse, the SS soldier immediately encounters Upham as he leaves the room... and simply walks past him, down the stairs, as Upham lies totally powerless in terror. The sheer emotional tension going on in the scene is bone-chilling.
Even worse an armed Upham was just a few meters away hearing them struggle but too frightened to go help and that Mellish was also desperately calling the other guy who was with him for help, not aware that he was already dying / dead.
Oh, and that "other" guy? He's trying to breathe through a throat that just got shot open by a machinegun.
Miller and Co inspect a pile of dog tags of KIA soldiers, to see if Ryan's among them. The sheer size of the pile is pretty sobering, every one means another Mother is going to get a telegram..... and then they find the pair with the bullet hole through them.
Any of the battle scenes in the film could qualify. The filmmakers did a really good job of showing you how terrifying and dangerous battlefields are.
Jackson's death. He's sniping soldiers left and right, and has an open-topped Marder completely pinned down. Then he sees it: The remaining Tiger-A has found his position and is elevating its main gun on him. He barely has time to yell to his partner to get down before they're both killed. Even though it's quick, there's a shot of the side of his head caving in as the 88mm shell hits point-blank.
The sight of Horvath lying dead with his eyes open is quite unsettling.