"What's Next?" is the eighteenth and final episode of the third season of 9-1-1, and the forty-sixth episode overall. It aired on May 11, 2020.
The 118 rushes to save lives in the aftermath of a massive train derailment. 
- Travis Schuldt, who played Abby's fiancee Sam Egan in this episode, is married to Natalie Zea, who has a recurring role on 9-1-1: Lone Star as Zoe. 
- The fireplace in Athena's home that Michael and Bobby destroyed in "Powerless" is still unfinished, as mentioned by her.
- Buck mentions the fire truck dropping on him, an incident that occurred during "This Life We Choose".
- Rumer Willis who plays the role of Georgia is the daughter of Bruce Willis and Demi Moore.
- This episode takes place during the month of April 2020, as the following episode flashes forward 5 months into Maddie's pregnancy. 
- Eddie meets Abby for the first time.
9-1-1 3x18 Promo "What's Next?" (HD) Season Finale ft. Connie Britton
Preview The Two-Part Finale Continues Season 3 Ep. 18 9-1-1
Cast Chat A Heart-Stopping Season Finale Season 3 Ep. 18 9-1-1-1
The Making Of 9-1-1 Season Finale Season 3 Ep. 18 9-1-1
Athena Meets With A Victim Advocate Season 3 Ep. 18 9-1-1
Josh Comes To Maddie For Advice On His Statement Season 3 Ep. 18 9-1-1
Passengers Interact Before Train Derails Season 3 Ep. 18 9-1-1
Buck Spots Abby At The Scene Season 3 Ep. 18 9-1-1
Athena Is Angry With Michael & Bobby Season 3 Ep. 18 9-1-1
Buck & Eddie Try To Rescue Two People From The Train Season 3 Ep. 18 9-1-1