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 by getting stabbed in the chest by a combat knife. Slowly overpowered, the knife slowly sinking into his chest until he bleeds to death.
More so if you understand German, as the SS soldier is, with a slight mocking tone, telling Mellish to stop struggling so that his death will be easier.
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.
Several men at Omaha Beach graphically drown in the water due to their gear packs weighing them down, while trying to get them off.
James "Scotty" Doohan, D-Day vet who lost a thumb 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.
Jackson's death. He's sniping soldiers left and right, then a Marder focuses its turret 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 shell hits.
The sight of Horvath lying dead with his eyes open is quite unsettling.