Throughout the film during the search, the temperature is quoted to be over 100° however, Linda Hamilton isn't sweating. Her clothes aren't dirty. It was hot and she was out in the desert for that long. She'd be a filthy nasty, dirty, stinky sweaty mess.
When Sam lands in the Sheriff's helicopter to pick up Rachel we hear the engine and rotors winding down, but as seen in the rotor's reflection in the windows, and the tail rotor visible behind Sam, they are not turning. The same happens when the helicopter is started for take-off - then engines and rotors can be heard spooling up, but the rotors are visibly not moving at all.