When the GI is killed, his body is sitting against the truck. The view changes to a long shot as the Germans start firing mortars, and the body is gone.
When Saunders ask Doc if Little John will be ok, Doc replies, "Yes, sir." He wouldn't have called a noncom sir, especially since he'd been serving with Saunders and he always called him "sarge".
It is mentioned several times that Lt. Benton is an Artillery officer, yet he wears the crossed rifles of Infantry on his collar.
After reaching the checkpoint and the lieutenant tells Stone to continue, the truck is seen coming toward the camera and the lights for the scene are visible in the windshield and again in the side window as the truck passes the camera. Update: This also happens the first time Benton is seen. He's being driven to Saunders' squad and lights are seen in the windshield as the truck passes.