Major Baldwin's jeep is obviously a post-World War II model, with the visible differences being the jeep seen in the film had larger headlights, a gas tank filler neck and cap in a cutout in the left rear quarter panel (instead of under the driver's seat), and the axe and shovel were affixed under the right front door cutout (instead of under the left front cutout), all different from World War II jeeps.
When Baldwin and his unit arrive at the ammunition dump they're supposed to blow up, it consists of several small buildings and shacks. But the interior shots showing mountains of ammunition have no resemblance to the buildings they're supposed to be in: two of them are clearly gigantic tunnels ten or twenty times as long as the buildings that are supposedly being inspected.
The goof item below may give away important plot points.
Just after Collins (Glen Corbett) is killed, Major Baldwin (Jimmy Stewart) goes to close Collins eyes. There is a fly by Collins' right eye and as Maj Baldwin goes to close his eyes, Collins blinks his eyelid - despite being dead.