- Beautiful Dreamer: Clarke adds Bellamy's name to the list while watching him sleep.
- The Bus Came Back: Luna and the rest of the boat people return in this episode although all but Luna end up Back for the Dead due to ingesting irradiated fish.
- When the sick Grounders arrive at Arkadia, someone mentions when the Grounders sent Murphy to the arc to infect them all in the first season
- Murphy tells Emori he didn't have a choice about sleeping with Ontari.
- Luna asks if the ASR is punishment for her not taking the Flame in season 3.
- Raven tells Bellamy to remind Clarke about what happened the last time Jaha went looking for salvation.
- Double Standard: Rape, Female on Male: Murphy makes it clear that his sleeping with Ontari last season was not consensual.
- The Friend Nobody Likes: Members of Arkadia give Murphy a cold welcome after he returns (having ditched them in the season premiere)... but they take him back.
- Except Abby, who tells him she was worried about him and is glad he's back.
- Hope Spot:
- Jaha reveals to Clarke and Bellamy that there is a potential fallout shelter made by a band of fanatics before the bombs dropped and that it could potentially hold thousands of people. Unfortunately once they actually reach said shelter they find nothing but a mass graveyard and realise that it's not a viable solution.
- Murphy gives Abby the medicine necessary to potentially save a Floukru girl from radiation sickness. Unfortunately it's too late for the medicine to be effective and she ends up dying.
- Laser-Guided Karma: Obviously not but Luna asks Clarke if her people dying is the result of her refusing The Flame last season.
- Pet the Dog: Murphy steals the radiation medicine for Abby and gives it to her after learning about the radiation that will soon arrive.
- Ship Tease: Jaha comments that Clarke is "lucky to have [Bellamy]" because he keeps her centered; Bellamy thinks that Clarke keeps him centered instead. At the end, they add each other's names to the list of survivors.
Recap / The 100 S 04 E 03