6 great 'call backs' the joint the Star Wars movies up.
When we say call backs we're talking about how the 7 Star Wars movies each have moments where they reference each other. Here's 6 moments where the script writers took the time to match things up.
Things that go bump on the Death Star
Remember that Storm Trooper that bumped his head in A New Hope?
That goof became the stuff of legend among Star Wars fans so much so that when Lucas decided Jango Fett was to be the 'father' of the Clone Army, this 'bump' was called back as an actual character trait of Jango.
During Attack of the Clones, when the Mandalorian gets into his ship after his tete a tete with Obi-Wan, he bangs his head on the open door.
Grand Moff Tarrkin's Revenge of the Sith blink and you'll miss him cameo

Tarkin is the dude who ordered the destruction of planet Alderaan, the home of the Organa family and millions of other voices.
A quick character cameo occurs at the end of Revenge of the Sith when Vader and the Emperor are standing on the bridge of a Star Destroyer, overlooking the initial construction stage of the Death Star.
In a blink an you'll miss it moment, a younger Tarkin quietly sidles up to the Sith Lords.
Vader's murder of the Younglings
Killing of the Younglings in Revenge of the Sith was a pretty obvious severe call back to the prior film, the Attack of the Clones.
While the murder is off screen, it is blatant what the freshly anointed Vader has just done.
He has murdered innocent children and there's nothing so subtle as that.
The call back is to the prior film, Attack of the Clones. Recall the scene where in front of the Younglings, Obi Wan and Yoda chat about how Obi want has lost a planet (how embarrassing!).
This is the same type of class where Yoda is teaching young ones about being a Jedi.
In hindsight, it's a brutal set up.
I've got a bad feeling about this
This line is stated by so many major characters, you just expect this line to be in every Star Wars movie you see.
"I love you:
So said Leia to Han as he was about to be frozen in carbonite. Ford's ad libbed reply of" I Know" is the stuff of Hollywood legend.
The call back came in Jedi when just after Han Solo grabbed Leia's breasts, the lines were reversed.
"You will die"
During Revenge of the Sith Mace Windu and Palpatine have battled it out and Windu has won the duel (something Yoda couldn't do, even when Mace had softened the Emperor up for him). Palpatine is no longer pretending he is anything but a Sith Lord.
And he launches a lightning bolt attack on Windu with the words "you will die".
This is a call back to Jedi when Luke has resolved not to kill his father and join the Dark Side which pisses of the Emperor who confirms Luke is now a Jedi and then stuns him with a bolt or a few thousand of Force lighting.
He takes a pause and say's "And now, you will die". Great work script writers, great work.
The Force Awakens
The Force Awakens film was bascially a well executed re hash of all the famous Star Wars moments, revisited in different guises.
Jakku is a stand in for Tatooine, Rey's heroism matches Luke, Maz's Castle can be likened to the Cantina etc.
The movie is basically a greatest hits of the Star Wars universe and there's one hit which we think is a brilliant call back to the film that started it all, A New Hope.
When Finn is tending to Chewbacca's injury he looks for something to use. And he pulls out the training remote that Luke used under Obi Wan tutelage, 30 odd years before hand. It's a blink and you'll miss moment but it was a nice wink to the past.
And if you didn't like that, this little factoid may brighten you smile.
You know when Finn bumps the digital chess board (the game is actually called Dejarik) ... the game the starts up is the uncompleted game that Chewbacca and R2D2 played in A New Hope!