The narrative conventions in action movie trailers typically involve: 1) Showing characters living stable lives at first, then introducing a problem or conflict through fast-paced scenes. 2) Ending with an enigma or cliffhanger to engage viewers and make them wonder what will happen next. 3) Using restricted narratives that don't reveal too much and encourage viewers to watch the full movie. Common enigmas center around who is behind threats or conflicts facing the main characters. Fast pacing, fade outs, and montages are used to create these enigmas and suspense.