After the release of Star Wars: The Last Jedi, a common refrain amongst a very vocal group of fans was, "That's not how the Force works..."
But going through and rewatching Star Wars Rebels, the animated series that just wrapped after four brilliant seasons, the seeds for the Force powers on display in Rian Johnson's Star Wars film had all been planted all along in an era before the original trilogy even took place.
One of the most visible Force powers that seemed new to some fans was the ability to communicate face-to-face via the Force. Force projection is something that first appeared in a second-season episode of Star Wars Rebels, called "Shroud of Darkness." While inside the Jedi temple on Lothal, Yoda appears before Ezra from the safety of Dagobah, sitting on a log. They speak of many important things. Namely, Yoda has begun to question the motives of the Jedi and how they participated in the Clone Wars and wielded the Force like a weapon.
This philosophy is a lesson Luke would only half-learn by the time The Last Jedi rolls around. There's some impression that this sort of communication can only happen where one of the participants is in a place strong with the Force. Between Ezra being inside a Jedi Temple and Dagobah being as strong in the Force as it is, they have no trouble communicating.
It's no wonder that Luke was able to focus his projection on Crait so capably from the site of the first Jedi temple on Ahch-To. Luke, arguably one of the most powerful force-wielders to have ever lived, is able to improve on this technique to the point where he was able to fool Kylo Ren and the entire Resistance into thinking he was there on the mineral planet of Crait.
There are even more mysterious things that happen inside of Jedi temples than Yoda appearing. The Jedi are given visions and hear voices and it is brought to the forefront of Star Wars Rebels a number of times. The Jedi temple on Lothal eventually becomes a lynchpin of the galaxy, and it shares some traits with the Jedi Library on Ahch-To. In the final episodes of Rebels, Ezra is drawn back to the temple after a vision. When Rey first discovers the library, if you listen closely, you can hear the tree whispering the Jedi code to her. When she gets to the tree itself, she realizes that she's seen the place before, but only in her dreams.
When Ezra and Kanan enter the temple on Lothal, there are lines and circles etched into the floor and when they tap into the force to enter the temple, there is a reaction with the natural world. On Rebels, those lines light up a bright blue and grant them access. Those same lines are present on the floor of the temple on Ahch-To, but when Luke taps into the Force there, that physical manifestation comes in disturbing the pool of water that bears the symbol of the Prime Jedi.
One striking moment that echoed between Rebels and The Last Jedi that might have gone unnoticed occurs when both Ezra and Rey unwittingly tap into the dark side of the Force. Both send pebbles, dirt, and debris spinning into the around them.
Kanan and Leia both share similar moments through the course of Rebels and The Last Jedi as well. At one point on the show, Maul lures Kanan and Ezra to his space station and once he separates them, he jettisons Kanan out of an airlock. With no space suit or rebreather, Kanan has nothing but his wits and the Force to save him. Reaching out, he pulls himself through the vacuum into the hangar bay of the ship, the cold of space crystalizing against him. Leia is able to do a similar thing in The Last Jedi. Sensing her son ready to fire and missiles on the way, she braces herself. She's sucked out of the airlock and, through her wits and the Force, is able to pull herself back to the Raddus in one of the most striking moments in the film.
Another facet of the Force that seemed to have gone generally unaddressed during the classic six episodes of the saga, is the Force's connection to the natural world. We saw moments of it, when the Force connected the Naboo to the Gungans or Luke to the Ewoks, but not to the degree that Rebels has brought us. Even in early episodes, Ezra Bridger showed an affinity for his connection with nature. And, like Qui-Gon says, midi-chlorians, the microscopic life forms that exist in all living cells, connect all life to the mystery of the Force.
In the beginning, Ezra taps into this power to communicate with the aggressive fyrnocks by confronting the truth of the fate of his parents. Similarly, Rey must also confront the fate of her parents to take her Force powers to the next level. But Ezra is able to bond with the natural world and that bond grows. From fyrnocks to Loth-cats and eventually Loth-wolves. These animals share this connection with nature that the Empire flatly ignores, willing to destroy everything in pursuit of their goals.
Loth-wolves share moments in Rebels that come at us just like the crystal fox-like vulptexes that appear on Crait at the end of The Last Jedi. With their connection to the Force, they lead Poe Dameron, General Organa, and the rest of the Resistance to the hidden passage out of the cave that lets them escape the vile clutches of Kylo Ren and the First Order.
Going back to The Clone Wars, there are even more connections between the Force, the animated shows, and The Last Jedi, but, like Maz Kanata said, that's a good question for another time.