Although his choice to help with the droid attack on the Wookiees seemed to be a prudent one in Star Wars: Episode III - Revenge of the Sith, Yoda's Kashyyyk mission was actually his worst mistake. The decision came at a pivotal time for the Jedi Order, as a number of high-ranking masters were already spread across the galaxy providing aid to star systems under Separatist duress. Yoda's failed mission to Kashyyyk was the last in a long line of dominoes arranged by Palpatine in his coup against the Jedi Order, and with Yoda now absent from Coruscant, Palpatine was presented with the perfect time to strike.
Despite Yoda's established rapport with Chewbacca, Tarfful, and other members of the wroshyr tree-dwelling Wookiees, his decision to abandon Coruscant in favor of lending aid on Kashyyyk in Revenge of the Sith proved to be a crucial blunder. This impactful error in judgment from Yoda left the decision to confront Palpatine in Mace Windu's hands, a choice that was rushed and ill-advised. Windu's faithful allegiance to the Republic ultimately benefited Palpatine, as he was able to ensnare the Jedi and fully complete the turn of Anakin Skywalker to Darth Vader.
Yoda Would Have Handled The Sith Revelation Better Than Mace Windu
Yoda is undoubtedly one of the wisest Jedi to have ever lived in Star Wars canon, but his decision to leave Coruscant at such a critical juncture in Revenge of the Sith was his biggest oversight. Yoda's Kashyyyk mission meant that the ensuing political crisis surrounding Palpatine was left to Mace Windu, who was much less fit to address the secretive Sith Lord. Yoda's status as the Jedi Council's Grand Master wasn't unwarranted, as his prevailing loyalties lay with the galaxy's citizens and his fellow council members, rather than Palpatine's long-corrupted political machine that masked as the Galactic Republic.
Mace Windu's undying fidelity to the Republic was exhibited in Tales of the Jedi, as his by-the-book approach and strict adherence to the supposed rules drew the ire of Dooku. Given that Yoda wasn't quite as attached to the Republic as Windu, he would have handled Palpatine's reveal in Revenge of the Sith much more adeptly than Windu. Windu was far more concerned with the welfare of the Republic and Senate at large, leading him to rush in a state of panic right into the trap Palpatine laid. It's likely that Yoda would have handled this situation differently, electing to devise a more carefully deliberated strategy.
How Would Revenge Of The Sith Have Played Out With Yoda On Coruscant?
While it's difficult to say whether the outcome of Order 66 would have been altered had Yoda's Kashyyyk mission been halted, it's certainly up for discussion. Yoda likely would have acted as a much-needed voice of reason to counter Windu's aggression. The shrewd, small-statured Jedi Master likely would have devised a well-thought-out plan as opposed to blindly rushing in to confront one of the most powerful beings in the galaxy. Yoda's absence from Coruscant in Revenge of the Sith makes the events that unfold during Windu's attempted arrest of Palpatine that much more tragic, as they could have potentially been prevented with just a hint of patience.
If Yoda remained on Coruscant, he likely would not have attempted to arrest Palpatine with the haste that Windu displayed. But, if Yoda did eventually choose to challenge Palpatine alongside Windu, perhaps Revenge of the Sith's Fate would have been shifted. Although Palpatine may have allowed Windu to deafeat him, it appeared that Mace was more than a match for the Sith Lord. Yoda's subsequent duel with Palpatine in the Senate chamber and the fact that Palpatine tried to flee before the fight even began exhibited Palpatine's fear. With Yoda and Windu's combined strength, they likely would have been able to overpower Palpatine, foiling his plan to execute Order 66.
Did Palpatine Know Yoda Would Go To Kashyyyk?
While Palpatine may not have actively played a role in Yoda's Kashyyyk mission in Revenge of the Sith, the dark lord certainly held great influence over the circumstances that led to Yoda's choice. Part of the crux of this equation boils down to Palpatine's overarching schemes to lure the Jedi away from Coruscant. Palpatine warned Anakin that if any Jedi were to survive Order 66, civil war would follow. However, Palpatine's plot to eliminate the Jedi began long before he tasked Anakin with going to the Jedi Temple to carry out his bidding.
Palpatine successfully manipulated the Jedi Order into gradually dispersing members of the order away from the capital, leaving them crippled by the time they learn of his sinister nature. Obi-Wan Kenobi, Ki-Adi-Mundi, Aayla Secura, Plo Koon, and several other notable Jedi weren't present on Coruscant to aid in Palpatine's arrest. While it's unconfirmed whether Palpatine directly intended for Yoda's Kashyyyk mission to come to fruition, given the other Jedi the Sith Lord had perfectly positioned, it's not an unreasonable assumption. Ultimately, as a result of Yoda's crucial error, Palpatine's plans succeeded, making the end of Star Wars: Episode III - Revenge of the Sith that much more tragic.