The discussion revolves around understanding how images are formed by two mirrors in a periscope setup. Participants emphasize the importance of extending the mirrors to determine the correct image positions, noting that images in flat mirrors appear directly behind them and are not magnified. There is confusion regarding the correct answer choices, with participants debating the implications of perpendicular lines and distances in relation to the mirrors. The concept that the line joining an object and its image must be perpendicular to the mirror is reiterated. Ultimately, the discussion aims to clarify the principles of reflection and image formation in mirrors.