After the German half track slaughtered the GI's in the small valley, the German soldiers came to check out if any the GI's were alive. One German soldier checked the GI who was half off the front end the US vehicle. The dead GI moved his hand to grab hold of a handle so not to fall off the truck. The German seemed to notice the movement.
The cases of explosives in the two trucks are not secured in any way. With the way the drivers were going, and the condition of the roads, some of the cases above the tailgate could have bounced out.
The front left tire of Sloan's truck breaks through the rotting wood of the bridge and gets stuck, throwing Sloan down the embankment. Kirby and Littlejohn go down to help him. Sgt. Rose uses the grappling hook and his truck to pull Sloan's truck across the bridge, with no one steering Sloan's truck. The audience does not see how Rose managed to do this without getting the tire out of the hole.
When Sloan is driving his truck over the bridge that's not too safe, if he had gone as fast as Sgt. Rose told him to, he would have hit Rose's truck because he didn't move it far enough off the bridge.