The invite is important because without Romeo going to the the party he would have never met Juliet.

The ring is what symbolizes Romeo and Juliet's Marriage That starts off the turmoil of conflict.

The sleeping potion that Friar Lawrence gives to Juliet shows just how far Juliet is willing to go to be with romeo

The undelivered letter to romeo from the Friar is important because it lead to a deadly misunderstanding.

The poison Romeo buys in Mantua shows his desire to be with Juliet is strong enough to drive him to suicide.

Romeos dagger that Juliet uses to kill herself once she realizes that Romeo is dead