At 77:44 to 77:56 in the movie (mm:ss), Richard Gere is standing in front of a mirror. The problem is that the man in the mirror is not quite doing the same things as Richard Gere is.
I remember that part. Although it is supposed to be like that to signify that after the phone calls and strange happenings he was no longer alone and the mothman was basically screwing with his reflection.