Although Ryan is trapped for hours in a room with temperatures over 100 degrees, he barely sweats, and there are no sweat stains on his shirt. In addition, he spends much time on the dirty floor, exhausted, but his white shirt remains clean throughout the movie.
Two shots are fired with a small-caliber semi-automatic pistol. Following each shot we hear a metallic sound that's supposed to be that of an ejected cartridge case hitting the floor. But the sound is coming from something much heavier than an empty case.