One interesting plot twist could be that when they travel back in time, they accidentally change a major event that alters the entire ninja world. For example, they might prevent the Uchiha massacre, which would have a huge impact on characters like Sasuke and Itachi. This could lead to a completely different power dynamic in the hidden villages.
Maybe they travel to a time before the Akatsuki was formed. Tayuya could then try to stop her future self from joining the Akatsuki. Naruto, on the other hand, might try to influence some of the future villains to become good. This would create a lot of internal conflict within the characters as they struggle with changing the past and its consequences.
One possible plot twist could be that Naruto and Tayuya travel back to a time when the Hidden Leaf Village was first founded. This would put them in the middle of the early power struggles and they might have to use their future knowledge to prevent a great disaster. For example, they could stop a rogue ninja from stealing important village secrets that could have changed the course of the village's history.
One interesting plot twist could be that when they travel back in time, they accidentally change an event that was crucial for the formation of their friendship. So instead of being friends or at least allies later in life, they become enemies in the new timeline. Another could be that they go back to a time when their villages were at war, and they have to work together secretly to stop the war without revealing their time - traveling identities.
One interesting plot twist could be that when Naruto and Mito time travel, they accidentally change a major event in the Uzumaki clan's history. For example, they prevent the destruction of a powerful Uzumaki artifact that was originally lost. This could then lead to a whole new power dynamic in the Naruto universe, as other villages might try to steal or ally with the Uzumaki clan for this newfound power.
Maybe they travel back to their early days at the ninja academy. Naruto, who now has all his future knowledge, tries to befriend Sasuke in a different way. But Sasuke, being suspicious, thinks Naruto has some ulterior motive. This leads to a whole new set of comical and at the same time tense interactions between them as they both have to deal with their past selves and the changes they want to make.
One interesting plot twist could be that the Sannin travel back to a time when Orochimaru was still a good - hearted ninja. They could try to prevent his fall to the dark side. This would change the entire future of the Naruto world as Orochimaru's actions had a huge impact on many events.
Perhaps a really cool plot twist is that the time travel was actually a trap set by an old enemy. When Kakashi and Naruto travel back, they find out that this enemy has been manipulating events from the past all along. They then have to not only fix the past but also figure out a way to stop this enemy from using the past to destroy their future.
Well, a cool plot twist could be that Naruto and Mito time travel to a period right before the Nine - Tails was sealed in Mito. Naruto, with his knowledge of the future, tries to find an alternative way to deal with the Nine - Tails' power. This could completely change the history of the Uzumaki clan and the Hidden Leaf. Also, they could time travel to a time when the first Hokage was still alive and Naruto has to convince him of future threats without revealing too much. Or perhaps they travel to a time when a powerful enemy was about to attack the village, and they use their future skills to defeat the enemy in a way that shocks everyone in the past.
One interesting plot twist could be that Naruto travels back in time and discovers that the Hidden Leaf Village was founded on a much darker secret than he ever knew. This changes his perception of the village's history and his role in it.
Another plot could involve a love triangle between Naruto, Tayuya, and Kin. Naruto might be initially attracted to Kin's mysterious nature, while Tayuya has a fiery passion for Naruto. Kin could be conflicted between her loyalty to her own goals and her growing feelings for Naruto. This could lead to a lot of drama and emotional turmoil as they all navigate their relationships.
One idea could be Naruto somehow finds himself in a situation where he has to team up with Tayuya frequently. As they interact more, a harem starts to form around Naruto, with Tayuya being one of the key members. The plot could involve them going on missions together and Naruto gradually realizing his feelings for Tayuya among the others in the harem.