Warning: SPOILERS for episode #282 of Boruto.
A huge mistake in the one of the most iconic scenes in Naruto.
Sasuke's Story is set a few years after the ending of the original series, but before the start of Boruto. Naruto has accomplished his dream and become the Seventh Hokage, while his eternal friend/rival Sasuke decided to play a role as "the Hokage's shadow". When a mysterious illness affects Naruto, Sasuke (later ed by his wife Sakura) travels to the faraway land of Redaku to retrace the steps of the Sage of the Six Paths, who was once afflicted by the same illness. The manga adaptation of the light novel has been very well received, and the Sasuke's Story anime was quickly announced, integrated into Boruto, starting on January 8.
When the first episode of Sasuke Retsuden aired, however, fans immediately noticed that something was amiss. In a few frames of episode #282 of Boruto, Sasuke appears with both of his arms. This happens after the Uchiha has successfully infiltrated the Tartar Observatory, a maximum security prison that hides the clues of how the Sage of the Six Paths defeated his mysterious illness. Some prisoners pick up a fight with Sasuke and are quickly dispatched, and at that point one quick frame shows the protagonist with both of his arms. Naruto fans know that this is impossible, as Sasuke lost his left arm during his final battle against Naruto in the Valley of the End, and refused to have it replaced.
Sasuke's Lost Arm Represents The Ending Of Naruto
While most fans understood that this was just a minor oversight, deriving from the stress of producing a weekly anime, others chastised Studio Pierrot for the mistake, taking the chance to further berate Boruto, which has been the subject of harsh criticism for a while. This particular mistake is certainly small (as it happens only in a second-long frame), but it got inflated because Sasuke's lost arm has such a huge meaning. The Uchiha's refusal to get a prosthetic (like Naruto did) symbolizes his desire to atone for his past sins against Konoha. Also, the shot of Naruto and Sasuke lying on the ground after their final battle is perhaps the most iconic in the entire series. The blood from their severed arms connects them, mirroring the broken fingers from the destroyed statues of Hashirama and Madara ing in the shinobi's Seal of Reconciliation, symbolizing the rapprochement between the two friends and the end of the Uchiha's cycle of hatred.
As Studio Pierrot is currently also busy with Bleach: Thousand-Year Blood War, it's understandable that overworked animators can make small mistakes. However, fans who are already unhappy with Boruto took this chance to criticize the anime again, and Sasuke's lost arm has such a huge meaning for Naruto that it was impossible to miss this oversight.
Boruto is currently available on streaming from Crunchyroll.