In the beginning montage, the hubcaps of the camera-car can been seen in low angle shots of J.C. riding his bike, the camera motor can be distinctly heard in the quiet indoor scenes with J.C. and Kim, and the boom mike shows up so often it practically becomes another character in the movie.
Boom microphone is clearly visible (not just a bit but very obviously visible & moving back & forth between character dialogue), in the porch scene where the sheriff and deputy (Slim Pickens & Burr DeBenning), pay a call to J.C. and his sister, (Joanna Moore).