Season 3 of The Mandalorian ended with an unexpected reveal as the truth of Moff Gideon's sinister schemes was unveiled. Since the Disney+ Star Wars series began, it had been teasing the Imperial Remnant's interest in the science of cloning and, in particular, the ability to create clones who could wield the Force. Many fans assumed this was all building towards the Empire's resurrection of Emperor Palpatine, as seen in Star Wars: The Rise of Skywalker.
Ultimately, it was revealed that the work of Dr. Pershing (The Mandalorian's Imperial scientist who had been researching cloning) was all in aid of Moff Gideon's plan to create Force-sensitive clones of himself. The Season 3 finale revealed Gideon's clones, who were killed by Din Djarin before they could leave their incubators. It was also revealed that Gideon had been keeping his cloning experiments a secret from the rest of the Imperial Remnant, ensuring Pershing's research died with him. So why didn't the series address the creation of Palpatine's Force-sensitive clone body?
Somehow, Palpatine Returned... But How?
Palpatine's resurrection was revealed to the galaxy in The Rise of Skywalker, and the film infamously left out any explanation as to how exactly he returned. However, the machinations behind Palpatine's resurrection on the Sith world of Exegol were explored in greater depth in the novelization of The Rise of Skywalker. In the book, it was revealed Palpatine's plan to evade death had started long before the events of the sequel trilogy. In fact, Palpatine's return wasn't so much a resurrection as an evasion of death in the first place, with his clone body already prepared by the time of Return of the Jedi.
In the novel Star Wars: The Rise of Skywalker: Expanded Edition, it is revealed that the Sith Eternal cult on Exegol had started creating a clone body for Palpatine while he was still Emperor. Their initial experiments had been unsuccessful and most had not survived. These experiments also led to the creation of a strand-cast -- a clone who is not an exact duplicate of the original host -- who was not Force-sensitive but would become the father of Rey. However, ultimately one viable clone body was created. As Palpatine was thrown down the second Death Star's reactor shaft by Darth Vader, he transferred his consciousness out of his original body and into this clone, but his power in the dark side caused the body to start decaying.
Palpatine's Return Could Still be Explored in a Disney+ Star Wars Series
Since the body inhabited by Palpatine in The Rise of Skywalker was created before the original Star Wars trilogy even came to an end, there was never any real scope for The Mandalorian to explore the Emperor's resurrection. The Sith Eternal's efforts to prevent the Emperor's death had already given Palpatine his new form before The Mandalorian began. While this new body was not perfect, it was the one in which Palpatine would remain until the emergence of his granddaughter provided an opportunity for his spirit to pass into a new vessel.
While The Mandalorian takes place too late in the Star Wars timeline to explain Palpatine's return, another Star Wars series might be able to address the process by which the Emperor evaded death. Star Wars: The Bad Batch has already touched upon the Empire's interest in cloning. Season 2 saw the Empire capture the Kaminoan Chief Medical Scientist, Nala Se, who was instrumental in the creation of the Republic's Clone Army. She has been taken into Imperial custody to work on a project for the Emperor -- a project Nala Se has deemed impossible. Season 3 may see her playing a role in Palpatine's plans to avoid death.