Lando Calrissian making an appearance for the first time in the new trilogy. 

In the beginning of the film, Rey and her team land on planet Pasaana, which is celebrating its Festival of Ancestors. They are attacked and then saved by a masked bystander; only to find out it is Lando Calrissian himself. Lando is an old friend to characters like Han Solo and Princess Leia and was in the original trilogy. During their encounter, he mentions to the group to "send his love to Leia", which is a nod at the long lasting love he has for after all of the years gone by.

Luke Skywalker can finally lift the X-Wing.

Although Luke Skywalker has passed on, his spirit remains in the force and thus with Rey. He nicely helps her retrieve her sunken ship, as he uses his powers of the force to lift it up. Any long time Star Wars fans will immediately see the connection it holds to "Star Wars: Episode IV", when Yoda does the same for a young Luke Skywalker when he was in training.

This could be a nod at the past film, or a nice full-circle situation that Luke has always been the powerful Jedi we knew he could become.

Rey and Princess Leia say goodbye for the last time. 

The death of Carrie Fisher broke the world's heart. Her character Princess Leia was a legendary icon for the series, and J.J. Abrams was able to give her the send off she deserved. Although she is in several other scenes after this, I believe this was the moment that allowed the fourth wall to break. Her embrace with Rey is the last scene they share together in the film, which almost seems like we are all giving her a goodbye hug too.

Rey hears the voices of past Jedi when she takes down Emperor Palpatine. 

During the final moments of the battle between Rey and the Emperor, Rey believes that all hope is lost for her and the galaxy. With one final hope, she stands and uses the force to call out to the Jedi before her for help. Not only do they give her the strength that she needs, but they call out to her.

Some of the voices that we hear belong to: Anikan Skywaler, Obi Wan Kenobi, Qui-Got Jin, Yoda, and Mace Windu. These characters were all powerful Jedi that we have watched rise and fall in the original 6 films. This gives both Rey and the audience the sense that these characters will always be with us.