When Steve and Dan are standing by the jeep at the end of the road, the boom's reflection is visible in the windshield. Also, when Steve and Sally are in the convertible, it is visible in the in the wing window.
When Steve and Dan are in the cave, Steve's shirt is wet from perspiration (under the arms) on the front, but not the back. When he turns to talk to Dan, the shirt is suddenly dry. In the next shot, the stains are back.