The race is on to stop Pan from enacting another curse on the residents of Storybrooke.
Back from the Dead: The Blue Fairy/Mother Superior. After the death of the Shadow (the one responsible for taking her shadow and killing her), she is revived.
Bittersweet Ending: Pan does die, but Gold has to kill himself for that to happen. Also, all the Storybrooke characters return to the Enchanted Forest, with Storybrooke disappearing completely, but Emma and Henry have to stay behind, without any memories of what has happened throughout the entire show.
Call Back: Grumpy is again the one who announces the arrival of the curse.
Killed Off for Real: Felix, The Shadow, Pan and Rumplestiltskin/Gold all meet their ends in this episode.
Power Nullifier: The cuff that Pan invented keeps magic users from using their powers. It doesn't work on him, though, since he anticipated it might be used against him.
Peter: Never build a cage you can't get out of.
Self-Sacrifice Scheme: Rumple knew the only way that he could kill Pan was for he himself to die in the process. So he used his shadow to bring back the Dark One dagger in order to impale himself along with Pan, meaning he dies, Pan becomes the Dark One but since the dagger is impaled in him too, he also dies, ending the Dark One curse forever.
Series Fauxnale: Many have noted that everything is tied up so neatly in the end and the feeling of coming full circle is so great that this episode could very well be mistaken for the end of the series had it not been for literally it's last minute.
Sequel Hook: Literally, as it's Hook who comes in at the last minute to set up the next story arc.
Talking Is a Free Action: That is one considerate curse, as it gives all our heroes ample time to talk through everything they need to.