Revealing mistake: When Norman MacLean drops off Neal Burns after he falls asleep naked in the sun, Neal gets out of the car still naked with his clothes bundled in front of him. The camera angle switches to the rear view and the sunburn makeup on his back makes it look like he was wearing a bikini. His butt and back must have touched the car seat and rubbed off the makeup.
Continuity mistake: When Norman fishes with Paul for the first time after returning from Dartmouth, his fly reel changes three times in one scene. The first view of the reel it's a brand new Pflueger reel. The next view it's a worn and beat up reel. And the final view it's a Hardy reel.