WARNING: The following contains spoilers for Boruto: Naruto Next Generations Episode 168, "Training Begins!" now streaming on Crunchyroll.
The Boruto anime has quite a few nods to the original Naruto series, which makes sense as the younger generation of shinobi in Konoha interact with their parents and the older heads in general quite often. We see throwbacks to the wars the Great Nations fought and witness the younger ninja evolving the moves handed down to them by previous generations.
One such case is the Rasengan. Boruto wants to improve the technique, making it even more powerful than Naruto, Jiraiya or his grandfather, Minato, ever did. Impressively, after working assiduously in training, Boruto nails the power-up in the latest episode, but the another surprise comes with how the aftermath remixes Kakashi and Naruto's most epic moment from the Shippuden.
After Deepa beat Team 7 up and left Mitsuki near death, Boruto trains with Kakashi, a master of the Rasengan himself, but the war veteran admits that because Boruto doesn't have Kurama, the Nail Tails Fox his dad has inside him, the move wouldn't be as powerful. Eventually, they find ways to work around that problem, with Boruto better understanding the change in "nature" and "flow" of chakra.
When he first developed the Rasengan, Kakashi subconsciously applied lightning-natured chakra to it, which he mentions has its benefits. Upon throwing the projectile, the nature transformation abruptly activates, making it invisible, duping opponents into dropping their guard. However, when it does connect, the damage inflicted is exponentially greater, which helped Kakashi when he and Naruto used the Rasengan against Momoshiki. But now, using wind-natured chakra and controlling the chakra bomb with a shadow clone -- a move Naruto used to show he was a prodigy -- Boruto can perform the Wind Release: Rasengan, which destroys a giant boulder.
It leaves Kakashi speechless and, honestly, grateful he didn't follow through on his instincts and avoid training the annoying lad. It's fast, powerful and going to be tough for even the strongest shinobi to defend against, and it can still be powered up. However, it's drained Boruto's chakra immensely and he faints, only for Kakashi to catch him on his back, thinking how he inherited Minato's (Kakashi's teacher) genius and Naruto's unpredictability. More importantly, as the sleeping Boruto props on his sensei, it's a nice throwback to when Naruto saved Konoha from the Akatsuki.
He expelled a lot of energy fighting Pain and Co., and after getting Nagato to resurrect the village, including Kakashi, Naruto went through the woods outside of Konoha and fainted. However, Kakashi appeared out of nowhere to catch him the same way, thinking to himself how heavy Naruto had gotten since he was a baby. His sensei gives him a piggyback ride back to the village where everyone embraces Naruto, treating him like a celebrity for his heroics, a far cry from his days as an outcast. He wasn't unconscious like Boruto, though, making for a very warm father-son moment for the duo. And ironically, Kakashi recreates that moment, right after telling Boruto how lucky he is to have family and friends that love him in a time where there's relative peace in Konoha and most nations.