Let's stop and think for a bit. In overview, saving Greg's life started a chain reaction of events.
1) Saving him, allowed Greg to contact Tamara and reveal Storyrbooke's location to her. This lead to them attempting to destroy Storybrooke, and kidnapping Henry for (unknown to them) Pan.
2) After the adventure in Neverland, Pan managed to sneak back to Storybrooke to turn it into his New Neverland. This forced Regina to undo her curse to send everyone back.
3) That lead to fighting Zelena, who wanted to travel back in time to change her fate.
4) Emma and Hook got sucked into Zelena's time portal and accidentally brought the urn with Elsa in it to the present. This lead to the Snow Queen's insane plan, and Elsa reunited with her sister Anna.
5) Anna revealed Mr. Gold's past with her, leading him being banished by Belle and him teaming up with the Queens of Darkness to get their happy endings.
6) The darkness escaped Gold and Emma forced it to possess her. This lead to her sharing some of it with Hook to save his life, but he was coerced back to evil to enact his revenge.
7) Hook gives his life to stop the Darkness' plan, and Emma heads to the Underworld to save him. Ultimately, the Olympian Crystal ended up in Gold's possession and he tethered Storybrooke's magic to it.
8) Because of Gold's actions, David, Snow, Hook and Zelena ended up in the Land of Untold Stories and were followed back by Mr. Hyde. Dr. Jekyll even gave Regina a serum to split herself from the Evil Queen.
9) The Evil Queen attempts to ruin everyone's lives, ending up causing Gideon Gold's accelerated birth and kidnapping by the Black Fairy.
Did anyone else noticed this?