Sgt Saunders gets into the river to lay charges under a bridge. After he emerges from the water, he tends to Sgt Turk but is now completely dry.
The squad is to carry 100 pounds of explosives to the bridge. When the wooden crates are taken off the truck, they are handled as if empty. When the individual cardboard boxes of explosives are removed from the crates, they are empty.
When Saunders hits the German with his rifle butt, it's an obvious double with black hair for Saunders. The same is true when Saunders dives into the river after setting the charges.
American small arms fire passes right through thick gravestones but German small arms and MG fire does not.