Saga Lines or actions that could have ended the saga

Luke hestated a bit more and the deathstar destroys Yavin.

 

Anakin: "I can't do it, Mom."
Shmi: "How could I even think of letting you go? Good day, Mr. Qui-Gin; you're not taking my son anywhere."

 

OBI-WAN: I have a bad feeling about this.
QUI-GON: Me too, let's just go home.

 

Yoda and Mace fly by Palpatine's balcony while he's chatting with Maul.

 

Palpatine falls off the balcony in the Phantom Menace.

 

The Jedi don't accept baby Dooku (remember that he was Qui-Gon's Master) into the Order.

 

LUKE: Who is she? She's beautiful.

C-3PO: Artoo says... ah... (oh dear)… "Don't even think about it, farmboy. She's your sister."

LUKE: Oh... forget it then. Erase the message.