Although the show seems to be focused on bounty hunting, the title and the titular character led to speculation that other Mandalorians will appear such as Bo-Katan Kryze (who actually did come back in "The Heiress") and Fenn Rau, especially since these two are played by experienced screenactors and even resemble them. Helped in that both of their actors follow the show's official account on Twitter.
There was speculation that Ming-Na Wen was cast as a live-action version of Ursa Wren. This one wound up jossed, however, when a trailer revealed she's actually playing an assassin named Fennec Shand.
Observant viewers have noticed that the patch on Dr. Pershing's uniform matches that on Kaminoan doctors that worked on the Clone Troopers. Whatever that and First-Episode Twist mean have been tossed around on social media, most popularly that either the Empire is trying to make Force-sensitive clones or Palpatine is trying to study Yoda's species' in order to achieve immortality. Assisted is that the given age of the child (50) means that he was born the same year as Anakin Skywalker.
With the big deal the show makes about Mandalorians never taking their helmets off, there was some speculation that eventually the Mandalorian would get his helmet forcibly taken off and it wouldn't be Pedro Pascal underneath. Some even suspected the show would pull a Samus Is a Girl, given the long hair the character has in childhood flashbacks. When the character was finally unmasked in "Redemption" he turned out to be Pedro Pascal after all.
The fifth episode ends with a mysterious individual (only seen from the knees down) approaching Fennec's (probably) dead body. Many have noted that the jingling sound of their spurs and the radio transmission that heralds their arrival sounds exactly like Boba Fett's from The Empire Strikes Back, not to mention that this occurs on Tatooine, which was where Fett seemingly met his doom 5 years prior. Others, however, see this as a deliberate misdirection, and have speculated that the mystery person is a returning Greef Karga, an Early-Bird Cameo of Moff Gideon or Mayfeld, or (in the case that it is actually a previously-established character) Cad Bane. Chapter 14, "The Tragedy," would reveal that the mysterious individual was indeed Boba Fett.
A Varietyinterview with Ludwig Göransson, released a few months before the second season premiere, showed a picture of Pedro Pascal attending a scoring session while wearing a battle-worn variant of Boba Fett's helmet. It helped spark a few new theories about Season 2 events, such as Din Djarin getting shot in the head, or Boba Fett coming Back from the Dead after falling into the Sarlacc Pit. However, it ultimately turned out the helmet came from Göransson's personal collection of Star Wars memorabilia.
After the reveal of Boba Fett at the end of the Season 2 premiere, some fans remained skeptical that it was actually him, and suggested Temuera Morrison might actually be playing another popular clone character like Rex or Echo, though these are unlikely as any clone sans Boba would be well into their eighties due to their speeded aging factor. Chapter 14, "The Tragedy," would show that this figure was indeed Boba, as he looks the same, is wearing the same clothes, has the same weapons, and openly states that he is Boba Fett.
There have been pervasive rumors pushed mostly by some vocal fans who disliked the sequel trilogy, that this series either takes place in an alternate timeline, or is setting up a Cosmic Retcon that would negate the events of the sequel trilogy.
Quite a few fans have taken the fact that Plo Koon was the Jedi the actors were told was coming for Grogu as evidence he survived Order 66, with Disney Gallery episode #10's (fake) artwork of him rescuing the party only adding fuel to the fire.
Some viewers speculate that the show's title actually refers to Grogu, whom they predict will someday take up Din's Mandalorian customs.
News that Christopher Lloyd had been cast for Season 3 drove many fans to speculate which role will he play, with some saying he'll play Joruus C'baoth or Grogu's voice. He ended up playing a former Separatist named Helgait.
The Book of Boba Fett shifting focus to Din in the last few episodes, to the extent that Boba went two whole episodes without saying anything, prompted Boba fans to either predict or insist that at least one Mandalorian Season 3 chapter would focus entirely on him instead of Din, to balance things out.
Some fans suspect that the Armourer might be a Zabrak like Darth Maul because of the tiny spikes on her helmet. Which leads to another theory where she is in cahoots with the bad guys for reasons known only to her.
A map in Star Wars: Dawn of Rebellion: The Visual Guide places Aq Vetina close to Dathomir, inspiring fans to find a connection between the Nightsisters and Din Djarin's red-clad biological family.
with Ludwig Göransson, released a few months before the second season premiere, showed a picture